______________________________________________________________________
21 Strings library [lib.strings]
______________________________________________________________________
1 This clause describes components for manipulating sequences of "char-
acters," where characters may be of any POD (_basic.types_) type. In
this clause such types are called char-like types, and objects of
char-like types are called char-like objects or simply "characters."
2 The following subclauses describe a character traits class, a string
class, and null-terminated sequence utilities, as summarized in Table
1:
Table 1--Strings library summary
+---------------------------------------------------------------+
| Subclause Header(s) |
+---------------------------------------------------------------+
|_lib.char.traits_ Character traits <string> |
+---------------------------------------------------------------+
|_lib.string.classes_ String classes <string> |
+---------------------------------------------------------------+
| <cctype> |
| <cwctype> |
|_lib.c.strings_ Null-terminated sequence utilities <cstring> |
| <cwchar> |
| <cstdlib> |
+---------------------------------------------------------------+
21.1 Character traits [lib.char.traits]
1 This subclause defines requirements on classes representing character
traits, and defines a class template char_traits<charT>, along with
two specializations, char_traits<char> and char_traits<wchar_t>, that
satisfy those requirements.
2 Most classes specified in clauses _lib.string.classes_ and
_lib.input.output_ need a set of related types and functions to com-
plete the definition of their semantics. These types and functions
are provided as a set of member typedefs and functions in the template
parameter `traits' used by each such template. This subclause defines
the semantics guaranteed by these members.
3 To specialize those templates to generate a string or iostream class
to handle a particular character container type CharT, that and its
related character traits class Traits is passed as a pair of parame-
ters to the string or iostream template as formal parameters charT and
traits.
4 This subclause specifies a struct template, char_traits<charT>, with
no members, to appear in the header <string> along with two explicit
specializations of it, char_traits<char> and char_traits<wchar_t>
which satisfy the requirements below.
21.1.1 Definitions [lib.char.traits.defs]
1 Additional definitions of terms:
--character: In clauses _lib.strings_, _lib.localization_, and
_lib.input.output_, the term character means any object which, when
treated sequentially, can represent text. The term does not only
mean char and wchar_t objects, but any value which can be repre-
sented by a type which provides the definitions specified in this
clause.
--character container type: A character container type is a class or a
type used to represent a character. It is used for one of the tem-
plate parameters of the string and iostream class templates. A
character container class shall be a POD (_basic.types_) type.
--traits: Traits is a class which encapsulates a set of the defined
types and functions necessary for handling character objects in any
implementation of the string and iostream libraries.
--NTCTS: A null-terminated character type string is a sequence of
character type, that precede the termination null character type
value charT(0).
21.1.2 Character traits requirements [lib.char.traits.require]
1 In Table 2, X denotes a Traits class defining types and functions for
the character container type CharT; c and d denote values of type
CharT; p and q denote values of type const CharT*; s denotes a value
of type CharT*; n, i and j denote values of type size_t; e and f
denote values of type X::int_type; pos denotes a value of type
X::pos_type; and state denotes a value of type X::state_type;
Table 2--Traits requirements
-------------------------------------------------------------------------------------------
expression return type assertion/note complexity
pre/post-condition
-------------------------------------------------------------------------------------------
X::char_type charT (described in _lib.char.traits.typedefs_) compile-time
-------------------------------------------------------------------------------------------
X::int_type (described in _lib.char.traits.typedefs_) compile-time
-------------------------------------------------------------------------------------------
X::off_type (described in _lib.char.traits.typedefs_) compile-time
-------------------------------------------------------------------------------------------
X::pos_type (described in _lib.char.traits.typedefs_) compile-time
-------------------------------------------------------------------------------------------
X::state_type (described in _lib.char.traits.typedefs_) compile-time
-------------------------------------------------------------------------------------------
X::assign(c,d) (not used) assigns c=d. constant
-------------------------------------------------------------------------------------------
X::eq(c,d) bool yields: whether c is to be treated as constant
equal to d.
-------------------------------------------------------------------------------------------
X::lt(c,d) bool yields: whether c is to be treated as constant
less than d.
-------------------------------------------------------------------------------------------
X::compare int yields: 0 if for each i in [0,n), linear
(p,q,n) X::eq(p[i],q[i]) is true; else, a nega-
tive value if, for some j in [0,n),
X::lt(p[j],q[j]) is true and for each i
in [0,j) X::eq(p[i],q[i]) is true; else a
positive value.
-------------------------------------------------------------------------------------------
X::length(p) size_t yields: the smallest i such that linear
X::eq(p[i],charT(0)) is true.
-------------------------------------------------------------------------------------------
X::find(p,n,c) const X:: yields: the smallest q in [p,p+n) such linear
char_type* that X::eq(q,c) is true, zero otherwise.
-------------------------------------------------------------------------------------------
X::move(s,p,n) X:: for each i in [0,n), performs X::as- linear
char_type* sign(s[i],p[i]). Copies correctly even
where p is in [s,s+n). yields: s+n.
-------------------------------------------------------------------------------------------
X::copy(s,p,n) X:: pre: p not in [s,s+n). yields: s+n. for linear
char_type* each i in [0,n), performs X::as-
sign(s[i],p[i]).
-------------------------------------------------------------------------------------------
X::assign X:: for each i in [0,n), performs X::as- linear
(s,n,c) char_type* sign(s[i],c). yields: s.
-------------------------------------------------------------------------------------------
X::not_eof(e) int_type yields: e if X::eq(e,X::eof()) is false, constant
otherwise a value f such that
| |
| |
| |
| |
| X::eq(f,X::eof()) is false. |
+-----------------------------------------------------------------------------------------+
|X:: X:: yields: if for some c, constant |
|to_char_type(e) char_type X::eq_int_type(e,X::to_int_type(c)) is |
| true, c; else some unspecified value. |
+-----------------------------------------------------------------------------------------+
|X::to_int_type X:: yields: some value e, constrained by the constant |
|(c) int_type definitions of to_char_type and |
| eq_int_type. |
+-----------------------------------------------------------------------------------------+
|X::eq_int_type bool yields: for all c and d, X::eq(c,d) is constant |
|(e,f) equal to |
| X::eq_int_type(X::to_int_type(c), |
| X::to_int_type(d)); otherwise, yields |
| true if e and f are both copies of |
| X::eof(). |
+-----------------------------------------------------------------------------------------+
|X::get_state X:: yields: state representing the conversion constant |
|(pos) state_type state in pos. |
+-----------------------------------------------------------------------------------------+
|X::eof() X:: yields: a value e such that constant |
| int_type X::eq_int_type(e,X::to_int_type(c)) is |
| false for all values c. |
+-----------------------------------------------------------------------------------------+
2 The struct template
template<class charT> struct char_traits { };
shall be provided in the header <string> as a basis for explicit spe-
cializations.
3 In the following subclauses, the token charT represents the parameter
of the traits template.
21.1.3 traits typedefs [lib.char.traits.typedefs]
typedef CHAR_T char_type;
1 The type char_type is used to refer to the character container type in
the implementation of the library classes defined in
_lib.string.classes_ and _lib.input.output_.
typedef INT_T int_type;
Requires:
For a certain character container type char_type, a related con-
tainer type INT_T shall be a type or class which can represent all
of the valid characters converted from the corresponding char_type
values, as well as an end-of-file value, eof(). The type int_type
represents another character container type which can hold end-of-
file to be used as a return type of the iostream class member func-
tions.
typedef OFF_T off_type;
Requires:
For a streambuf or its derived classes specialized for CHAR_T and
TRAIT_T, a type or class, OFF_T is used to define off_type in the
traits and represents offsets to positional information for the spe-
cialized streambuf (or its derived) class.1)
2 It is used to represent:
--a signed displacement, measured in characters, from a specified
position within a sequence.
--an absolute position within a sequence.
3 The value OFF_T(-1) can be used as an error indicator.
4 The effect of passing to any function in _lib.input.output_ an OFF_T
value not obtained from a function defined in that clause (for exam-
ple, an arbitrary integer) is undefined except where otherwise noted.
5 Convertible to type POS_T. But no validity of the resulting POS_T
value is ensured, whether or not the OFF_T value is valid.2)
typedef POS_T pos_type;
Requires:
For a streambuf or its derived classed specialized for CHAR_T and
TRAIT_T, a type or class, POS_T is used to define pos_type for the
seek operation. It can hold all the information necessary to repo-
sition the specialized streambuf (or its derived) class.
6 The type pos_type represents the type used for the seek operation in
the implementation of streambuf and its derived classes in this
library.
typedef STATE_T state_type;
Requires:
For a streambuf or its derived classes whose underlying stream is a
multibyte character stream and specialized for CHAR_T and TRAIT_T, a
type or class STATE_T is used to define state_type in the traits and
represents the conversion state type or class which is applied to
the codecvt<> facet defined in _lib.localization_.
_________________________
1) It is usually a synonym for one of the signed basic integral types
whose representation has at least as many bits as type long.
2) An implementation may use the same type for both OFF_T and POS_T.
21.1.4 char_traits [lib.char.traits.specializations]
specializations
namespace std {
template<> struct char_traits<char>;
template<> struct char_traits<wchar_t>;
}
1 The header <string> declares two structs that are specializations of
the template struct char_traits.
2 The struct char_traits<char> is the char type specialization of the
template struct char_traits, which contains all of the types and func-
tions necessary to ensure the behaviours of the classes in
_lib.string.classes_ and _lib.input.output_.
3 The types and static member functions are described in detail in
_lib.char.traits.require_.
21.1.4.1 struct [lib.char.traits.specializations.char]
char_traits<char>
namespace std {
template<>
struct char_traits<char> {
typedef char char_type;
typedef int int_type;
typedef streamoff off_type;
typedef streampos pos_type;
typedef mbstate_t state_type;
static void assign(char_type& c1, const char_type& c2);
static bool eq(const char_type& c1, const char_type& c2);
static bool lt(const char_type& c1, const char_type& c2);
static int compare(const char_type* s1, const char_type* s2, size_t n);
static size_t length(const char_type* s);
static const char_type* find(const char_type* s, int n,
const char_type& a);
static char_type* move(char_type* s1, const char_type* s2, size_t n);
static char_type* copy(char_type* s1, const char_type* s2, size_t n);
static char_type* assign(char_type* s, size_t n, char_type a);
static int_type not_eof(const int_type& c);
static char_type to_char_type(const int_type& c);
static int_type to_int_type(const char_type& c);
static bool eq_int_type(const int_type& c1, const int_type& c2);
static state_type get_state(pos_type pos);
static int_type eof();
};
}
1 The header <string> (_lib.string.classes_) declares a specialization
of the template struct char_traits for char. It is for narrow-ori-
ented iostream classes.
2 The defined types for int_type, pos_type, off_type, and state_type are
int, streampos, streamoff, and mbstate_t respectively.
3 The type streampos is an implementation-defined type that satisfies
the requirements for POS_T in _lib.char.traits.typedefs_.
4 The type streamoff is an implementation-defined type that satisfies
the requirements for OFF_T in _lib.char.traits.typedefs_.
5 The type mbstate_t is defined in <cwchar> and can represent any of the
conversion states possible to occur in an implementation-defined set
of supported multibyte character encoding rules.
6 The two-argument members assign, eq, and lt are defined identically to
the built-in operators =, ==, and < respectively.
21.1.4.2 struct [lib.char.traits.specializations.wchar.t]
char_traits<wchar_t>
namespace std {
template<>
struct char_traits<wchar_t> {
typedef wchar_t char_type;
typedef wint_t int_type;
typedef wstreamoff off_type;
typedef wstreampos pos_type;
typedef mbstate_t state_type;
static void assign(char_type& c1, const char_type& c2);
static bool eq(const char_type& c1, const char_type& c2);
static bool lt(const char_type& c1, const char_type& c2);
static int compare(const char_type* s1, const char_type* s2, size_t n);
static size_t length(const char_type* s);
static const char_type* find(const char_type* s, int n,
const char_type& a);
static char_type* move(char_type* s1, const char_type* s2, size_t n);
static char_type* copy(char_type* s1, const char_type* s2, size_t n);
static char_type* assign(char_type* s, size_t n, char_type a);
static int_type not_eof(const int_type& c);
static char_type to_char_type(const int_type& c);
static int_type to_int_type(const char_type& c);
static bool eq_int_type(const int_type& c1, const int_type& c2);
static state_type get_state(pos_type pos);
static int_type eof();
};
}
The header <string> (_lib.string.classes_) declares a specialization
of the template struct char_traits for wchar_t. It is for wide-ori-
ented iostream classes.
1 The defined types for int_type, pos_type, off_type, and state_type are
wint_t, wstreampos, wstreamoff, and mbstate_t respectively.
2 The type wstreampos is an implementation-defined type that satisfies
the requirements for POS_T in _lib.char.traits.typedefs_.
3 The type wstreamoff is an implementation-defined type that satisfies
the requirements for OFF_T in _lib.char.traits.typedefs_.
4 The pairs of types streampos and wstreampos, and streamoff and
wstreamoff may be different if such implementations that adopt no
shift encoding in narrow-oriented iostreams but supports one or more
shift encodings in wide-oriented streams.
5 The type mbstate_t is defined in <cwchar> and can represent any of the
conversion states possible to occur in an implementation-defined set
of supported multibyte character encoding rules.
6 The two-argument members assign, eq, and lt are defined identically to
the built-in operators =, ==, and < respectively.
21.2 String classes [lib.string.classes]
1 The header <string> defines a basic string class template and its
traits that can handle all char-like (_lib.strings_) template argu-
ments with several function signatures for manipulating varying-length
sequences of char-like objects.
2 The header <string> also defines two specific template classes string
and wstring and their special traits.
Header <string> synopsis
namespace std {
// subclause _lib.char.traits_, character traits:
template<class charT>
struct char_traits;
template <> struct char_traits<char>;
template <> struct char_traits<wchar_t>;
// subclause _lib.basic.string_, basic_string:
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT> >
class basic_string;
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs, charT rhs);
template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator==(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator!=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator< (const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator> (const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator<=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
bool operator>=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
// subclause _lib.string.special_:
template<class charT, class traits, class Allocator>
void swap(basic_string<charT,traits,Allocator>& lhs,
basic_string<charT,traits,Allocator>& rhs);
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
operator>>(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str);
template<class charT, class traits, class Allocator>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os,
const basic_string<charT,traits,Allocator>& str);
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
getline(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str,
charT delim);
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
getline(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str);
typedef basic_string<char> string;
typedef basic_string<wchar_t> wstring;
}
21.3 Template class basic_string [lib.basic.string]
1 For a char-like type charT, the template class basic_string describes
objects that can store a sequence consisting of a varying number of
arbitrary char-like objects (_lib.strings_). The first element of the
sequence is at position zero. Such a sequence is also called a
"string" if the given char-like type is clear from context. In the
rest of this clause, charT denotes such a given char-like type. Stor-
age for the string is allocated and freed as necessary by the member
functions of class basic_string.
2 The template class basic_string conforms to the requirements of a
Sequence, as specified in (_lib.sequence.reqmts_). Additionally,
because the iterators supported by basic_string are random access
iterators (_lib.random.access.iterators_), basic_string conforms to
the the requirements of a Reversible Container, as specified in
(_lib.container.requirements_).
3 In all cases, size() <= capacity().
4 The functions described in this clause can report two kinds of errors,
each associated with a distinct exception:
--a length error is associated with exceptions of type length_error
(_lib.length.error_);
--an out-of-range error is associated with exceptions of type
out_of_range (_lib.out.of.range_).
namespace std {
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT> >
class basic_string {
public:
// types:
typedef traits traits_type;
typedef typename traits::char_type value_type;
typedef Allocator allocator_type;
typedef typename Allocator::size_type size_type;
typedef typename Allocator::difference_type difference_type;
typedef typename Allocator::reference reference;
typedef typename Allocator::const_reference const_reference;
typedef typename Allocator::pointer pointer;
typedef typename Allocator::const_pointer const_pointer;
typedef implementation defined iterator; // See _lib.container.requirements_
typedef implementation defined const_iterator; // See _lib.container.requirements_
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
static const size_type npos = -1;
// _lib.string.cons_ construct/copy/destroy:
explicit basic_string(const Allocator& a = Allocator());
basic_string(const basic_string& str, size_type pos = 0,
size_type n = npos, const Allocator& a = Allocator());
basic_string(const charT* s, size_type n, const Allocator& a = Allocator());
basic_string(const charT* s, const Allocator& a = Allocator());
basic_string(size_type n, charT c, const Allocator& a = Allocator());
template<class InputIterator>
basic_string(InputIterator begin, InputIterator end,
const Allocator& a = Allocator());
~basic_string();
basic_string& operator=(const basic_string& str);
basic_string& operator=(const charT* s);
basic_string& operator=(charT c);
// _lib.string.iterators_ iterators:
iterator begin();
const_iterator begin() const;
iterator end();
const_iterator end() const;
reverse_iterator rbegin();
const_reverse_iterator rbegin() const;
reverse_iterator rend();
const_reverse_iterator rend() const;
// _lib.string.capacity_ capacity:
size_type size() const;
size_type length() const;
size_type max_size() const;
void resize(size_type n, charT c);
void resize(size_type n);
size_type capacity() const;
void reserve(size_type res_arg = 0);
void clear();
bool empty() const;
// _lib.string.access_ element access:
const_reference operator[](size_type pos) const;
reference operator[](size_type pos);
const_reference at(size_type n) const;
reference at(size_type n);
// _lib.string.modifiers_ modifiers:
basic_string& operator+=(const basic_string& str);
basic_string& operator+=(const charT* s);
basic_string& operator+=(charT c);
basic_string& append(const basic_string& str);
basic_string& append(const basic_string& str, size_type pos,
size_type n);
basic_string& append(const charT* s, size_type n);
basic_string& append(const charT* s);
basic_string& append(size_type n, charT c);
template<class InputIterator>
basic_string& append(InputIterator first, InputIterator last);
basic_string& assign(const basic_string&);
basic_string& assign(const basic_string& str, size_type pos,
size_type n);
basic_string& assign(const charT* s, size_type n);
basic_string& assign(const charT* s);
basic_string& assign(size_type n, charT c);
template<class InputIterator>
basic_string& assign(InputIterator first, InputIterator last);
basic_string& insert(size_type pos1, const basic_string& str);
basic_string& insert(size_type pos1, const basic_string& str,
size_type pos2, size_type n);
basic_string& insert(size_type pos, const charT* s, size_type n);
basic_string& insert(size_type pos, const charT* s);
basic_string& insert(size_type pos, size_type n, charT c);
iterator insert(iterator p, charT c = charT());
void insert(iterator p, size_type n, charT c);
template<class InputIterator>
void insert(iterator p, InputIterator first, InputIterator last);
basic_string& erase(size_type pos = 0, size_type n = npos);
iterator erase(iterator position);
iterator erase(iterator first, iterator last);
basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
size_type pos2, size_type n2);
basic_string& replace(size_type pos, size_type n1, const charT* s,
size_type n2);
basic_string& replace(size_type pos, size_type n1, const charT* s);
basic_string& replace(size_type pos, size_type n1, size_type n2, charT c);
basic_string& replace(iterator i1, iterator i2, const basic_string& str);
basic_string& replace(iterator i1, iterator i2, const charT* s, size_type n);
basic_string& replace(iterator i1, iterator i2, const charT* s);
basic_string& replace(iterator i1, iterator i2,
size_type n, charT c);
template<class InputIterator>
basic_string& replace(iterator i1, iterator i2,
InputIterator j1, InputIterator j2);
size_type copy(charT* s, size_type n, size_type pos = 0) const;
void swap(basic_string<charT,traits,Allocator>&);
// _lib.string.ops_ string operations:
const charT* c_str() const; // explicit
const charT* data() const;
allocator_type get_allocator() const;
size_type find (const basic_string& str, size_type pos = 0) const;
size_type find (const charT* s, size_type pos, size_type n) const;
size_type find (const charT* s, size_type pos = 0) const;
size_type find (charT c, size_type pos = 0) const;
size_type rfind(const basic_string& str, size_type pos = npos) const;
size_type rfind(const charT* s, size_type pos, size_type n) const;
size_type rfind(const charT* s, size_type pos = npos) const;
size_type rfind(charT c, size_type pos = npos) const;
size_type find_first_of(const basic_string& str, size_type pos = 0) const;
size_type find_first_of(const charT* s, size_type pos, size_type n) const;
size_type find_first_of(const charT* s, size_type pos = 0) const;
size_type find_first_of(charT c, size_type pos = 0) const;
size_type find_last_of (const basic_string& str,
size_type pos = npos) const;
size_type find_last_of (const charT* s, size_type pos, size_type n) const;
size_type find_last_of (const charT* s, size_type pos = npos) const;
size_type find_last_of (charT c, size_type pos = npos) const;
size_type find_first_not_of(const basic_string& str,
size_type pos = 0) const;
size_type find_first_not_of(const charT* s, size_type pos,
size_type n) const;
size_type find_first_not_of(const charT* s, size_type pos = 0) const;
size_type find_first_not_of(charT c, size_type pos = 0) const;
size_type find_last_not_of (const basic_string& str,
size_type pos = npos) const;
size_type find_last_not_of (const charT* s, size_type pos,
size_type n) const;
size_type find_last_not_of (const charT* s, size_type pos = npos) const;
size_type find_last_not_of (charT c, size_type pos = npos) const;
basic_string substr(size_type pos = 0, size_type n = npos) const;
int compare(const basic_string& str) const;
int compare(size_type pos1, size_type n1,
const basic_string& str) const;
int compare(size_type pos1, size_type n1,
const basic_string& str,
size_type pos2, size_type n2) const;
int compare(const charT* s) const;
int compare(size_type pos1, size_type n1,
const charT* s, size_type n2 = npos) const;
};
}
21.3.1 basic_string constructors [lib.string.cons]
1 In all basic_string constructors, a copy of the Allocator argument is
used for any memory allocation performed by the constructor or member
functions during the lifetime of the object.
explicit basic_string(const Allocator& a = Allocator());
Effects:
Constructs an object of class basic_string. The postconditions of
this function are indicated in Table 3:
Table 3--basic_string(const Allocator&) effects
+----------------------------------------------------------------------------+
| Element Value |
+----------------------------------------------------------------------------+
|data() a non-null pointer that is copyable and can have 0 added to it |
|size() 0 |
|capacity() an unspecified value |
+----------------------------------------------------------------------------+
basic_string(const basic_string<charT,traits,Allocator>& str,
size_type pos = 0, size_type n = npos,
const Allocator& a = Allocator());
Requires:
pos <= str.size()
Throws:
out_of_range if pos > str.size().
Effects:
Constructs an object of class basic_string and determines the effec-
tive length rlen of the initial string value as the smaller of n and
str.size() - pos, as indicated in Table 4:
Table 4--basic_string(basic_string,size_type,size_type,const Allocator&) effects
+------------------------------------------------------+
| Element Value |
+------------------------------------------------------+
|data() points at the first element of an |
| allocated copy of rlen consecutive |
| elements of the string controlled |
| by str beginning at position pos |
|size() rlen |
|capacity() a value at least as large as size() |
|get_allocator() str.get_allocator() |
+------------------------------------------------------+
basic_string(const charT* s, size_type n,
const Allocator& a = Allocator());
Requires:
s shall not be a null pointer and n < npos.
Throws:
out_of_range if n == npos.
Effects:
Constructs an object of class basic_string and determines its ini-
tial string value from the array of charT of length n whose first
element is designated by s, as indicated in Table 5:
Table 5--basic_string(const charT*,size_type, const Allocator&) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the array whose |
| first element is pointed at by s |
|size() n |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
basic_string(const charT* s, const Allocator& a = Allocator());
Requires:
s shall not be a null pointer.
Effects:
Constructs an object of class basic_string and determines its ini-
tial string value from the array of charT of length
traits::length(s) whose first element is designated by s, as indi-
cated in Table 6:
Table 6--basic_string(const charT*,const Allocator&) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the array whose |
| first element is pointed at by s |
|size() traits::length(s) |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
Notes:
Uses traits::length().
basic_string(size_type n, charT c, const Allocator& a = Allocator());
Requires:
n < npos
Throws:
length_error if n == npos.
Effects:
Constructs an object of class basic_string and determines its ini-
tial string value by repeating the char-like object c for all n ele-
ments, as indicated in Table 7:
Table 7--basic_string(size_type,charT,const Allocator&) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated array of n elements, each |
| storing the initial value c |
|size() n |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
template<class InputIterator>
basic_string(InputIterator begin, InputIterator end,
const Allocator& a = Allocator());
Effects:
Constructs a string from the values in the range [begin, end), as
indicated in Table 8:
Table 8--basic_string(InputIterator,InputIterator,const Allocator&) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the elements in |
| the range [begin,end) |
|size() distance between begin and end |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
Notes:
see clause _lib.sequence.reqmts_.
basic_string<charT,traits,Allocator>&
operator=(const basic_string<charT,traits,Allocator>& str);
Effects:
If *this and str are not the same object, modifies *this as shown in
Table 9:
Table 9--operator=(const basic_string<charT,traits,Allocator>&) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the array whose |
| first element is pointed at by |
| str.data() |
|size() str.size() |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
If *this and str are the same object, the member has no effect.
Returns:
*this
basic_string<charT,traits,Allocator>&
operator=(const charT* s);
Returns:
*this = basic_string<charT,traits,Allocator>(s).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>& operator=(charT c);
Returns:
*this = basic_string<charT,traits,Allocator>(1,c).
21.3.2 basic_string iterator support [lib.string.iterators]
iterator begin();
const_iterator begin() const;
Returns:
an iterator referring to the first character in the string.
iterator end();
const_iterator end() const;
Returns:
an iterator which is the past-the-end value.
reverse_iterator rbegin();
const_reverse_iterator rbegin() const;
Returns:
an iterator which is semantically equivalent to reverse_itera-
tor(end()).
reverse_iterator rend();
const_reverse_iterator rend() const;
Returns:
an iterator which is semantically equivalent to reverse_itera-
tor(begin()).
21.3.3 basic_string capacity [lib.string.capacity]
size_type size() const;
Returns:
a count of the number of char-like objects currently in the string.
size_type length() const;
Returns:
size().
size_type max_size() const;
Returns:
The maximum size of the string.
void resize(size_type n, charT c);
Requires:
n <= max_size()
Throws:
length_error if n > max_size().
Effects:
Alters the length of the string designated by *this as follows:
--If n <= size(), the function replaces the string designated by *this
with a string of length n whose elements are a copy of the initial
elements of the original string designated by *this.
--If n > size(), the function replaces the string designated by *this
with a string of length n whose first size() elements are a copy of
the original string designated by *this, and whose remaining ele-
ments are all initialized to c.
void resize(size_type n);
Effects:
resize(n,charT()).
size_type capacity() const;
Returns:
the size of the allocated storage in the string.
void reserve(size_type res_arg=0);
1 The member function reserve() is a directive that informs a
basic_string object of a planned change in size, so that it can manage
the storage allocation accordingly.
Effects:
After reserve(), capacity() is greater or equal to the argument of
reserve. Reallocation invalidates all the references, pointers, and
iterators referring to the elements in the sequence.
void clear();
Effects:
Behaves as if the function calls:
erase(begin(), end());
bool empty() const;
Returns:
size() == 0.
21.3.4 basic_string element access [lib.string.access]
const_reference operator[](size_type pos) const;
reference operator[](size_type pos);
Effects:
The reference returned is invalid after any subsequent call to
c_str(), data(), or any non-const member function for the object.
Returns:
If pos < size(), returns data()[pos]. Otherwise, if pos == size(),
the const version returns traits::eos(). Otherwise, the behavior is
undefined.
const_reference at(size_type pos) const;
reference at(size_type pos);
Requires:
pos < size()
Throws:
out_of_range if pos >= size().
Returns:
operator[](pos).
21.3.5 basic_string modifiers [lib.string.modifiers]
21.3.5.1 basic_string::operator+= [lib.string::op+=]
basic_string<charT,traits,Allocator>&
operator+=(const basic_string<charT,traits,Allocator>& str);
Returns:
append(str).
basic_string<charT,traits,Allocator>& operator+=(const charT* s);
Returns:
*this += basic_string<charT,traits,Allocator>(s).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>& operator+=(charT c);
Returns:
*this += basic_string<charT,traits,Allocator>(1,c).
21.3.5.2 basic_string::append [lib.string::append]
basic_string<charT,traits,Allocator>&
append(const basic_string<charT,traits>& str);
Returns:
append(str, 0, npos).
basic_string<charT,traits,Allocator>&
append(const basic_string<charT,traits>& str, size_type pos, size_type n);
Requires:
pos <= str.size()
Throws:
out_of_range if pos > str.size().
Effects:
Determines the effective length rlen of the string to append as the
smaller of n and str.size() - pos. The function then throws
length_error if size() >= npos - rlen.
Otherwise, the function replaces the string controlled by *this with
a string of length size() + rlen whose first size() elements are a
copy of the original string controlled by *this and whose remaining
elements are a copy of the initial elements of the string controlled
by str beginning at position pos.
Returns:
*this.
basic_string<charT,traits,Allocator>&
append(const charT* s, size_type n);
Returns:
append(basic_string<charT,traits,Allocator>(s,n)).
basic_string<charT,traits,Allocator>& append(const charT* s);
Returns:
append(basic_string<charT,traits,Allocator>(s)).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>&
append(size_type n, charT c);
Returns:
append(basic_string<charT,traits,Allocator>(n,c)).
template<class InputIterator>
basic_string& append(InputIterator first, InputIterator last);
Returns:
append(basic_string<charT,traits,Allocator>(first,last)).
21.3.5.3 basic_string::assign [lib.string::assign]
basic_string<charT,traits,Allocator>&
assign(const basic_string<charT,traits>& str);
Returns:
assign(str, 0, npos).
basic_string<charT,traits,Allocator>&
assign(const basic_string<charT,traits>& str, size_type pos,
size_type n);
Requires:
pos <= str.size()
Throws:
out_of_range if pos > str.size().
Effects:
Determines the effective length rlen of the string to assign as the
smaller of n and str.size() - pos.
The function then replaces the string controlled by *this with a
string of length rlen whose elements are a copy of the string con-
trolled by str beginning at position pos.
Returns:
*this.
basic_string<charT,traits,Allocator>&
assign(const charT* s, size_type n);
Returns:
assign(basic_string<charT,traits,Allocator>(s,n)).
basic_string<charT,traits,Allocator>& assign(const charT* s);
Returns:
assign(basic_string<charT, traits, Allocator>(s)).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>&
assign(size_type n, charT c);
Returns:
assign(basic_string<charT,traits,Allocator>(n,c)).
template<class InputIterator>
basic_string& assign(InputIterator first, InputIterator last);
Returns:
assign(basic_string<charT,traits,Allocator>(first,last)).
21.3.5.4 basic_string::insert [lib.string::insert]
basic_string<charT,traits,Allocator>&
insert(size_type pos1,
const basic_string<charT,traits,Allocator>& str);
Returns:
insert(pos1,str,0,npos).
basic_string<charT,traits,Allocator>&
insert(size_type pos1,
const basic_string<charT,traits,Allocator>& str,
size_type pos2, size_type n);
Requires
pos1 <= size() and pos2 <= str.size()
Throws:
out_of_range if pos1 > size() or pos2 > str.size().
Effects:
Determines the effective length rlen of the string to insert as the
smaller of n and str.size() - pos2. Then throws length_error if
size() >= npos - rlen.
Otherwise, the function replaces the string controlled by *this with
a string of length size() + rlen whose first pos1 elements are a
copy of the initial elements of the original string controlled by
*this, whose next rlen elements are a copy of the elements of the
string controlled by str beginning at position pos2, and whose
remaining elements are a copy of the remaining elements of the orig-
inal string controlled by *this.
Returns:
*this.
basic_string<charT,traits,Allocator>&
insert(size_type pos, const charT* s, size_type n);
Returns:
insert(pos,basic_string<charT,traits,Allocator>(s,n)).
basic_string<charT,traits,Allocator>&
insert(size_type pos, const charT* s);
Returns:
insert(pos,basic_string<charT,traits,Allocator>(s)).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>&
insert(size_type pos, size_type n, charT c);
Returns:
insert(pos,basic_string<charT,traits,Allocator>(n,c)).
iterator insert(iterator p, charT c);
Requires:
p is a valid iterator on *this.
Effects:
inserts a copy of c before the character referred to by p.
Returns:
an iterator which refers to the copy of the inserted character.
void insert(iterator p, size_type n, charT c);
Requires:
p is a valid iterator on *this.
Effects:
inserts n copies of c before the character referred to by p.
template<class InputIterator>
void insert(iterator p, InputIterator first, InputIterator last);
Requires:
p is a valid iterator on *this. [first,last) is a valid range.
Effects:
inserts copies of the characters in the range [first,last) before
the character referred to by p.
21.3.5.5 basic_string::erase [lib.string::erase]
basic_string<charT,traits,Allocator>&
erase(size_type pos = 0, size_type n = npos);
Requires:
pos <= size()
Throws:
out_of_range if pos > size().
Effects:
Determines the effective length xlen of the string to be removed as
the smaller of n and size() - pos.
The function then replaces the string controlled by *this with a
string of length size() - xlen whose first pos elements are a copy
of the initial elements of the original string controlled by *this,
and whose remaining elements are a copy of the elements of the orig-
inal string controlled by *this beginning at position pos + xlen.
Returns:
*this.
iterator erase(iterator p);
Requires:
p is a valid iterator on *this.
Effects:
removes the character referred to by p.
Returns:
an iterator which points to the element immediately following p
prior to the element being erased. If no such element exists, end()
is returned.
iterator erase(iterator first, iterator last);
Requires:
first and last are valid iterators on *this, defining a range
[first,last).
Effects:
removes the characters in the range [first,last).
Returns:
an iterator which points to the element immediately following last
prior to the element being erased. If no such element exists, end()
is returned.
21.3.5.6 basic_string::replace [lib.string::replace]
basic_string<charT,traits,Allocator>&
replace(size_type pos1, size_type n1,
const basic_string<charT,traits,Allocator>& str);
Returns:
replace(pos1, n1, str, 0, npos).
basic_string<charT,traits,Allocator>&
replace(size_type pos1, size_type n1,
const basic_string<charT,traits,Allocator>& str,
size_type pos2, size_type n2);
Requires:
pos1 <= size() && pos2 <= str.size().
Throws:
out_of_range if pos1 > size() or pos2 > str.size().
Effects:
Determines the effective length xlen of the string to be removed as
the smaller of n1 and size() - pos1. It also determines the effec-
tive length rlen of the string to be inserted as the smaller of n2
and str.size() - pos2 .
Throws length_error if size() - xlen >= npos - rlen.
Otherwise, the function replaces the string controlled by *this with
a string of length size() - xlen + rlen whose first pos1 elements
are a copy of the initial elements of the original string controlled
by *this, whose next rlen elements are a copy of the initial ele-
ments of the string controlled by str beginning at position pos2,
and whose remaining elements are a copy of the elements of the orig-
inal string controlled by *this beginning at position pos1 + xlen.
Returns:
*this.
basic_string<charT,traits,Allocator>&
replace(size_type pos, size_type n1, const charT* s, size_type n2);
Returns:
replace(pos,n1,basic_string<charT,traits,Allocator>(s,n2)).
basic_string<charT,traits,Allocator>&
replace(size_type pos, size_type n1, const charT* s);
Returns:
replace(pos,n1,basic_string<charT,traits,Allocator>(s)).
Notes:
Uses traits::length().
basic_string<charT,traits,Allocator>&
replace(size_type pos, size_type n1,
size_type n2, charT c);
Returns:
replace(pos,n1,basic_string<charT,traits,Allocator>(n2,c)).
basic_string& replace(iterator i1, iterator i2, const basic_string& str);
Requires:
The iterators i1 and i2 are valid iterators on *this, defining a
range [i1,i2).
Effects:
Replaces the string controlled by *this with a string of length
size() - (i2 - i1) + str.size() whose first begin() - i1 elements
are a copy of the initial elements of the original string controlled
by *this, whose next str.size() elements are a copy of the string
controlled by str, and whose remaining elements are a copy of the
elements of the original string controlled by *this beginning at
position i2.
Returns:
*this.
Notes:
After the call, the length of the string will be changed by:
str.size() - (i2 - i1).
basic_string&
replace(iterator i1, iterator i2, const charT* s, size_type n);
Returns:
replace(i1,i2,basic_string(s,n)).
Notes:
Length change: n - (i2 - i1).
basic_string& replace(iterator i1, iterator i2, const charT* s);
Returns:
replace(i1,i2,basic_string(s)).
Notes:
Length change: traits::length(s) - (i2 - i1).
Uses traits::length().
basic_string& replace(iterator i1, iterator i2, size_type n,
charT c);
Returns:
replace(i1,i2,basic_string(n,c)).
Notes:
Length change: n - (i2 - i1).
template<class InputIterator>
basic_string& replace(iterator i1, iterator i2,
InputIterator j1, InputIterator j2);
Returns:
replace(i1,i2,basic_string(j1,j2)).
Notes:
Length change: j2 - j1 - (i2 - i1).
21.3.5.7 basic_string::copy [lib.string::copy]
size_type copy(charT* s, size_type n, size_type pos = 0) const;
Requires:
pos <= size()
Throws:
out_of_range if pos > size().
Effects:
Determines the effective length rlen of the string to copy as the
smaller of n and size() - pos. s shall designate an array of at
least rlen elements.
The function then replaces the string designated by s with a string
of length rlen whose elements are a copy of the string controlled by
*this beginning at position pos.
The function does not append a null object to the string designated
by s.
Returns:
rlen.
21.3.5.8 basic_string::swap [lib.string::swap]
void swap(basic_string<charT,traits,Allocator>& s);
Effects:
Swaps the contents of the two strings.
Postcondition:
*this contains the characters that were in s, s contains the charac-
ters that were in *this.
Complexity:
constant time.
21.3.6 basic_string string operations [lib.string.ops]
const charT* c_str() const;
Returns:
A pointer to the initial element of an array of length size() + 1
whose first size() elements equal the corresponding elements of the
string controlled by *this and whose last element is a null charac-
ter specified by traits::eos().
Requires:
The program shall not alter any of the values stored in the array.
Nor shall the program treat the returned value as a valid pointer
value after any subsequent call to a non-const member function of
the class basic_string that designates the same object as this.
Notes:
Uses traits::eos().
const charT* data() const;
Returns:
If size() is nonzero, the member returns a pointer to the initial
element of an array whose first size() elements equal the corre-
sponding elements of the string controlled by *this. If size() is
zero, the member returns a non-null pointer that is copyable and can
have zero added to it.
Requires:
The program shall not alter any of the values stored in the charac-
ter array. Nor shall the program treat the returned value as a
valid pointer value after any subsequent call to a non- const member
function of basic_string that designates the same object as this.
allocator_type get_allocator() const;
Returns:
a copy of the Allocator object used to construct the string.
21.3.6.1 basic_string::find [lib.string::find]
size_type find(const basic_string<charT,traits,Allocator>& str,
size_type pos = 0) const;
Effects:
Determines the lowest position xpos, if possible, such that both of
the following conditions obtain:
--pos <= xpos and xpos + str.size() <= size();
--at(xpos+I) == str.at(I) for all elements I of the string controlled
by str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type find(const charT* s, size_type pos, size_type n) const;
Returns:
find(basic_string<charT,traits,Allocator>(s,n),pos).
size_type find(const charT* s, size_type pos = 0) const;
Returns:
find(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type find(charT c, size_type pos = 0) const;
Returns:
find(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.2 basic_string::rfind [lib.string::rfind]
size_type rfind(const basic_string<charT,traits,Allocator>& str,
size_type pos = npos) const;
Effects:
Determines the highest position xpos, if possible, such that both of
the following conditions obtain:
--xpos <= pos and xpos + str.size() <= size();
--at(xpos+I) == str.at(I) for all elements I of the string controlled
by str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type rfind(const charT* s, size_type pos, size_type n) const;
Returns:
rfind(basic_string<charT,traits,Allocator>(s,n),pos).
size_type rfind(const charT* s, size_type pos = npos) const;
Returns:
rfind(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type rfind(charT c, size_type pos = npos) const;
Returns:
rfind(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.3 basic_string::find_first_of [lib.string::find.first.of]
size_type
find_first_of(const basic_string<charT,traits,Allocator>& str,
size_type pos = 0) const;
Effects:
Determines the lowest position xpos, if possible, such that both of
the following conditions obtain:
--pos <= xpos and xpos < size();
--at(xpos) == str.at(I) for some element I of the string controlled by
str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type
find_first_of(const charT* s, size_type pos, size_type n) const;
Returns:
find_first_of(basic_string<charT,traits,Allocator>(s,n),pos).
size_type find_first_of(const charT* s, size_type pos = 0) const;
Returns:
find_first_of(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type find_first_of(charT c, size_type pos = 0) const;
Returns:
find_first_of(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.4 basic_string::find_last_of [lib.string::find.last.of]
size_type
find_last_of(const basic_string<charT,traits,Allocator>& str,
size_type pos = npos) const;
Effects:
Determines the highest position xpos, if possible, such that both of
the following conditions obtain:
--xpos <= pos and pos < size();
--at(xpos) == str.at(I) for some element I of the string controlled by
str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type find_last_of(const charT* s, size_type pos, size_type n) const;
Returns:
find_last_of(basic_string<charT,traits,Allocator>(s,n),pos).
size_type find_last_of(const charT* s, size_type pos = npos) const;
Returns:
find_last_of(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type find_last_of(charT c, size_type pos = npos) const;
Returns:
find_last_of(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.5 [lib.string::find.first.not.of]
basic_string::find_first_not_of
size_type
find_first_not_of(const basic_string<charT,traits,Allocator>& str,
size_type pos = 0) const;
Effects:
Determines the lowest position xpos, if possible, such that both of
the following conditions obtain:
--pos <= xpos and xpos < size();
--at(xpos) == str.at(I) for no element I of the string controlled by
str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type
find_first_not_of(const charT* s, size_type pos, size_type n) const;
Returns:
find_first_not_of(basic_string<charT,traits,Allocator>(s,n),pos).
size_type find_first_not_of(const charT* s, size_type pos = 0) const;
Returns:
find_first_not_of(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type find_first_not_of(charT c, size_type pos = 0) const;
Returns:
find_first_not_of(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.6 [lib.string::find.last.not.of]
basic_string::find_last_not_of
size_type
find_last_not_of(const basic_string<charT,traits,Allocator>& str,
size_type pos = npos) const;
Effects:
Determines the highest position xpos, if possible, such that both of
the following conditions obtain:
--xpos <= pos and pos < size();
--at(xpos) == str.at(I)) for no element I of the string controlled by
str.
Returns:
xpos if the function can determine such a value for xpos. Other-
wise, returns npos.
Notes:
Uses traits::eq().
size_type find_last_not_of(const charT* s, size_type pos,
size_type n) const;
Returns:
find_last_not_of(basic_string<charT,traits,Allocator>(s,n),pos).
size_type find_last_not_of(const charT* s, size_type pos = npos) const;
Returns:
find_last_not_of(basic_string<charT,traits,Allocator>(s),pos).
Notes:
Uses traits::length().
size_type find_last_not_of(charT c, size_type pos = npos) const;
Returns:
find_last_not_of(basic_string<charT,traits,Allocator>(1,c),pos).
21.3.6.7 basic_string::substr [lib.string::substr]
basic_string<charT,traits,Allocator>
substr(size_type pos = 0, size_type n = npos) const;
Requires:
pos <= size()
Throws:
out_of_range if pos > size().
Effects:
Determines the effective length rlen of the string to copy as the
smaller of n and size() - pos.
Returns:
basic_string<charT,traits,Allocator>(data()+pos,rlen).
21.3.6.8 basic_string::compare [lib.string::compare]
int compare(const basic_string<charT,traits,Allocator>& str)
Effects:
Determines the effective length rlen of the strings to compare as
the smallest of size() and str.size(). The function then compares
the two strings by calling traits::compare(data(), str.data(),
rlen).
Returns:
the nonzero result if the result of the comparison is nonzero. Oth-
erwise, returns a value as indicated in Table 10:
Table 10--compare() results
+------------------------------------+
| Condition Return Value |
+------------------------------------+
|size() < str.size() < 0 |
|size() == str.size() 0 |
|size() > str.size() > 0 |
+------------------------------------+
int compare(size_type pos1, size_type n1,
const basic_string<charT,traits,Allocator>& str) const;
Returns:
basic_string<charT,traits,Allocator>(*this,pos1,n1).compare(
str) .
int compare(size_type pos1, size_type n1,
const basic_string<charT,traits,Allocator>& str,
size_type pos2, size_type n2) const;
Returns:
basic_string<charT,traits,Allocator>(*this,pos1,n1).compare(
basic_string<charT,traits,Allocator>(str,pos2,n2)) .
int compare(const charT *s) const;
Returns:
this->compare(basic_string<charT,traits,Allocator>(s)).
int compare(size_type pos, size_type n1,
charT *s, size_type n2 = npos) const;
Returns:
basic_string<charT,traits,Allocator>(*this,pos,n1).compare(
basic_string<charT,traits,Allocator>(s,n2))
21.3.7 basic_string non-member functions [lib.string.nonmembers]
21.3.7.1 operator+ [lib.string::op+]
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs).append(rhs)
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) + rhs.
Notes:
Uses traits::length().
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(charT lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(1,lhs) + rhs.
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs + basic_string<charT,traits,Allocator>(rhs).
Notes:
Uses traits::length().
template<class charT, class traits, class Allocator>
basic_string<charT,traits,Allocator>
operator+(const basic_string<charT,traits,Allocator>& lhs,
charT rhs);
Returns:
lhs + basic_string<charT,traits,Allocator>(1,rhs).
21.3.7.2 operator== [lib.string::operator==]
template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
lhs.compare(rhs) == 0.
template<class charT, class traits, class Allocator>
bool operator==(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) == rhs.
template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs == basic_string<charT,traits,Allocator>(rhs).
Notes:
Uses traits::length().
21.3.7.3 operator!= [lib.string::op!=]
template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
!(lhs == rhs).
template<class charT, class traits, class Allocator>
bool operator!=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) != rhs.
template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs != basic_string<charT,traits,Allocator>(rhs).
Notes:
Uses traits::length().
21.3.7.4 operator< [lib.string::op<]
template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
lhs.compare(rhs) < 0.
template<class charT, class traits, class Allocator>
bool operator< (const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) < rhs.
template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs < basic_string<charT,traits,Allocator>(rhs).
21.3.7.5 operator> [lib.string::op>]
template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
lhs.compare(rhs) > 0.
template<class charT, class traits, class Allocator>
bool operator> (const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) > rhs.
template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs > basic_string<charT,traits,Allocator>(rhs).
21.3.7.6 operator<= [lib.string::op<=]
template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
lhs.compare(rhs) <= 0.
template<class charT, class traits, class Allocator>
bool operator<=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) <= rhs.
template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs <= basic_string<charT,traits,Allocator>(rhs).
21.3.7.7 operator>= [lib.string::op>=]
template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT,traits,Allocator>& lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
lhs.compare(rhs) >= 0.
template<class charT, class traits, class Allocator>
bool operator>=(const charT* lhs,
const basic_string<charT,traits,Allocator>& rhs);
Returns:
basic_string<charT,traits,Allocator>(lhs) >= rhs.
template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT,traits,Allocator>& lhs,
const charT* rhs);
Returns:
lhs >= basic_string<charT,traits,Allocator>(rhs).
21.3.7.8 swap [lib.string.special]
template<class charT, class traits, class Allocator>
void swap(basic_string<charT,traits,Allocator>& lhs,
basic_string<charT,traits,Allocator>& rhs);
Effects:
lhs.swap(rhs);
21.3.7.9 Inserters and extractors [lib.string.io]
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
operator>>(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str);
Effects:
Begins by constructing a sentry object k as if k were constructed by
basic_istream<charT,traits>::sentry k(is). If bool(k) is true, it
calls str.erase() and then extracts characters from is and appends
them to str as if by calling str.append(1,c). If is.width() is
greater than zero, the maximum number n of characters appended is
is.width(); otherwise n is str.max_size(). Characters are extracted
and appended until any of the following occurs:
--n characters are stored;
--end-of-file occurs on the input sequence;
--isspace(c,getloc()) is true for the next available input character
c. After the last character (if any) is extracted, is.width(0) is
called and the sentry object k is destroyed.
Returns:
is
template<class charT, class traits, class Allocator>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os,
const basic_string<charT,traits,Allocator>& str);
Effects:
Begins by constructing a sentry object k as if k were constructed by
basic_ostream<charT,traits>::sentry k(os). If bool(k) is true,
inserts characters as if by calling os.rdbuf()->sputn(str.data(),
n), padding as described in stage 3 of _lib.facet.num.put.virtuals_,
where n is the smaller of os.width() and str.size(); then calls
os.width(0). If the call to sputn fails, calls os.set-
state(ios_base::failbit).
Returns:
os
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
getline(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str,
charT delim);
Effects:
Begins by constructing a sentry object k as if by
basic_istream<charT,traits>::sentry k(is). If bool(k) is true, it
calls str.erase() and then extracts characters from is and appends
them to str as if by calling str.append(1,c) until any of the fol-
lowing occurs:
--end-of-file occurs on the input sequence (in which case, the getline
function calls is.setstate(ios_base::eofbit)).
--c == delim for the next available input character c (in which case,
c is extracted but not appended) (_lib.iostate.flags_)
--str.max_size() characters are stored (in which case, the function
calls is.setstate(ios_base::failbit) (_lib.iostate.flags_)
1 The conditions are tested in the order shown. In any case, after the
last character is extracted, the sentry object k is destroyed.
2 If the function extracts no characters, it calls is.set-
state(ios_base::failbit) which may throw ios_base::failure
(_lib.iostate.flags_).
Returns:
is.
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>&
getline(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str)
Returns:
getline(is,str,is.widen('\n'))
21.4 Null-terminated sequence utilities [lib.c.strings]
1 Tables 11, 12, 13, 14, and 15 describe headers <cctype>, <cwctype>,
<cstring>, <cwchar>, and <cstdlib> (multibyte conversions), respec-
tively.
Table 11--Header <cctype> synopsis
+-------------------------------------------------+
| Type Name(s) |
+-------------------------------------------------+
|Functions: |
|isalnum isdigit isprint isupper tolower |
|isalpha isgraph ispunct isxdigit toupper |
|iscntrl islower isspace |
+-------------------------------------------------+
Table 12--Header <cwctype> synopsis
+------------------------------------------------------------------+
| Type Name(s) |
+------------------------------------------------------------------+
|Macro: WEOF <cwctype> |
+------------------------------------------------------------------+
|Types: wctrans_t wctype_t wint_t <cwctype> |
+------------------------------------------------------------------+
|Functions: |
|iswalnum iswctype iswlower iswspace towctrans wctrans |
|iswalpha iswdigit iswprint iswupper towlower wctype |
|iswcntrl iswgraph iswpunct iswxdigit towupper |
+------------------------------------------------------------------+
Table 13--Header <cstring> synopsis
+-------------------------------------------------+
| Type Name(s) |
+-------------------------------------------------+
|Macro: NULL <cstring> |
+-------------------------------------------------+
|Type: size_t <cstring> |
+-------------------------------------------------+
|Functions: |
|memchr strcat strcspn strncpy strtok |
|memcmp strchr strerror strpbrk strxfrm |
|memcpy strcmp strlen strrchr |
|memmove strcoll strncat strspn |
|memset strcpy strncmp strstr |
+-------------------------------------------------+
Table 14--Header <cwchar> synopsis
+------------------------------------------------------------------------------+
| Type Name(s) |
+------------------------------------------------------------------------------+
|Macros: NULL <cwchar> WCHAR_MAX WCHAR_MIN WEOF <cwchar> |
+------------------------------------------------------------------------------+
|Types: mbstate_t wint_t <cwchar> size_t |
+------------------------------------------------------------------------------+
|Functions: |
|btowc getwchar ungetwc wcscpy wcsrtombs wmemchr |
|fgetwc mbrlen vfwprintf wcscspn wcsspn wmemcmp |
|fgetws mbrtowc vswprintf wcsftime wcsstr wmemcpy |
|fputwc mbsinit vwprintf wcslen wcstod wmemmove |
|fputws mbsrtowcs wcrtomb wcsncat wcstok wmemset |
|fwide putwc wcscat wcsncmp wcstol wprintf |
|fwprintf putwchar wcschr wcsncpy wcstoul wscanf |
|fwscanf swprintf wcscmp wcspbrk wcsxfrm |
|getwc swscanf wcscoll wcsrchr wctob |
+------------------------------------------------------------------------------+
Table 15--Header <cstdlib> synopsis
+------------------------------------------+
| Type Name(s) |
+------------------------------------------+
|Macros: MB_CUR_MAX |
+------------------------------------------+
|Functions: |
|atol mblen strtod wctomb |
|atof mbstowcs strtol wcstombs |
|atoi mbtowc strtoul |
+------------------------------------------+
2 The contents of these headers are the same as the Standard C library
headers <type.h>, <wctype.h>, <string.h>, <wchar.h>and <stdlib.h>
respectively, with the following modifications:
3 None of the headers shall define the type wchar_t (_lex.key_).
4 The function signature strchr(const char*, int) is replaced by the two
declarations:
const char* strchr(const char* s, int c);
char* strchr( char* s, int c);
5 both of which have the same behavior as the original declaration.
6 The function signature strpbrk(const char*, const char*) is replaced
by the two declarations:
const char* strpbrk(const char* s1, const char* s2);
char* strpbrk( char* s1, const char* s2);
7 both of which have the same behavior as the original declaration.
8 The function signature strrchr(const char*, int) is replaced by the
two declarations:
const char* strrchr(const char* s, int c);
char* strrchr( char* s, int c);
9 both of which have the same behavior as the original declaration.
10The function signature strstr(const char*, const char*) is replaced by
the two declarations:
const char* strstr(const char* s1, const char* s2);
char* strstr( char* s1, const char* s2);
11both of which have the same behavior as the original declaration.
12The function signature memchr(const void*, int, size_t) is replaced by
the two declarations:
const void* memchr(const void* s, int c, size_t n);
void* memchr( void* s, int c, size_t n);
13both of which have the same behavior as the original declaration.
14The function signature wcschr(const wchar_t*, wchar_t) is replaced by
the two declarations:
const wchar_t* wcschr(const wchar_t* s, wchar_t c);
wchar_t* wcschr( wchar_t* s, wchar_t c);
15both of which have the same behavior as the original declaration.
16The function signature wcspbrk(const wchar_t*, const wchar_t*) is
replaced by the two declarations:
const wchar_t* wcspbrk(const wchar_t* s1, const wchar_t* s2);
wchar_t* wcspbrk( wchar_t* s1, const wchar_t* s2);
17both of which have the same behavior as the original declaration.
18The function signature wcsrchr(const wchar_t*, wchar_t) is replaced by
the two declarations:
const wchar_t* wcsrchr(const wchar_t* s, wchar_t c);
wchar_t* wcsrchr( wchar_t* s, wchar_t c);
19both of which have the same behavior as the original declaration.
20The function signature wcsstr(const wchar_t*, const wchar_t*) is
replaced by the two declarations:
const wchar_t* wcsstr(const wchar_t* s1, const wchar_t* s2);
wchar_t* wcsstr( wchar_t* s1, const wchar_t* s2);
21both of which have the same behavior as the original declaration.
22The function signature wmemchr(const wwchar_t*, int, size_t) is
replaced by the two declarations:
const wchar_t* wmemchr(const wchar_t* s, wchar_t c, size_t n);
wchar_t* wmemchr( wchar_t* s, wchar_t c, size_t n);
23both of which have the same behavior as the original declaration.
SEE ALSO: ISO C subclauses 7.3, 7.10.7, 7.10.8, and 7.11. Amendment
1 subclauses 4.4, 4.5, and 4.6.