______________________________________________________________________
21 Strings library [lib.strings]
______________________________________________________________________
1 This clause describes components for manipulating sequences of "char
acters," where characters may be of type char, wchar_t, or of a type
defined in a C++ program.
2 The following subclauses describe string classes, and null-terminated
sequence utilities, as summarized in Table 1:
Table 1--Strings library summary
+---------------------------------------------------------------+
| Subclause Header(s) |
+---------------------------------------------------------------+
|_lib.string.classes_ String classes <string> |
+---------------------------------------------------------------+
| <cctype> |
| <cwctype> |
|_lib.c.strings_ Null-terminated sequence utilities <cstring> |
| <cwchar> |
| <cstdlib> |
+---------------------------------------------------------------+
21.1 String classes [lib.string.classes]
Header <string> synopsis
#include <memory> // for allocator
namespace std {
// subclause _lib.template.string_, basic_string:
template<class charT> struct string_char_traits;
template<class charT, class traits = string_char_traits<charT>,
class Allocator = allocator> 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_pointer 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);
template<class charT, class IS_traits,
class STR_traits, class STR_Alloc>
basic_istream<charT,IS_traits>&
operator>>(basic_istream<charT,IS_traits>& is,
basic_string<charT,STR_traits,STR_Alloc>& str);
template<class charT, class OS_traits,
class STR_traits, class STR_Alloc>
basic_ostream<charT, OS_traits>&
operator<<(basic_ostream<charT, OS_traits>& os,
const basic_string<charT,STR_traits,STR_Alloc>& str);
template<class charT, class IS_traits, class STR_traits, class STR_Alloc>
basic_istream<charT,IS_traits>&
getline(basic_istream<charT,IS_traits>& is,
basic_string<charT,STR_traits,STR_Alloc>& str,
charT delim = IS_traits::newline() );
// subclause _lib.string_, string:
struct string_char_traits<char>;
typedef basic_string<char> string;
// subclause _lib.wstring_, wstring:
struct string_char_traits<wchar_t>;
typedef basic_string<wchar_t> wstring;
}
1 In this subclause, we call the basic character types "char-like"
types, and also call the objects of char-like types "char-like"
objects or simply "character"s.
2 The header <string> defines a basic string class template and its
traits that can handle all "char-like" template arguments with several
function signatures for manipulating varying-length sequences of
"char-like" objects.
3 The header <string> also defines two specific template classes string
and wstring and their special traits.
21.1.1 Template class basic_string [lib.template.string]
21.1.1.1 Template class [lib.string.char.traits]
string_char_traits
namespace std {
template<class charT> struct string_char_traits {
typedef charT char_type; // for users to acquire the basic character type
static void assign(char_type& c1, const char_type& c2)
static bool eq(const char_type& c1, const char_type& c2)
static bool ne(const char_type& c1, const char_type& c2)
static bool lt(const char_type& c1, const char_type& c2)
static char_type eos(); // the null character
static basic_istream<charT>& char_in (basic_istream<charT>& is, char_type& a);
static basic_ostream<charT>& char_out(basic_ostream<charT>& os, char_type a);
static bool is_del(char_type a); // characteristic function for delimiters
// speed-up functions
static int compare(const char_type* s1, const char_type* s2, size_t n);
static size_t length(const char_type* s);
static char_type* copy(char_type* s1, const char_type* s2, size_t n);
};
}
21.1.1.2 string_char_traits [lib.string.char.traits.members]
members
1 Default definitions.
static void assign(char_type& c1, const char_type& c2)
Effects:
Assigns c2 to c1.
static bool eq(const char_type& c1, const char_type& c2)
Returns
c1 == c2
static bool ne(const char_type& c1, const char_type& c2)
Returns:
!(c1 == c2)
static bool lt(const char_type& c1, const char_type& c2)
Returns:
c1 < c2
static char_type eos();
Returns
The null character, char_type()
static basic_istream<charT>&
char_in(basic_istream<charT>& is, char_type& a);
Effects:
Extracts a charT object.
Returns:
is >> a
static basic_ostream<charT>&
char_out(basic_ostream<charT>& os, char_type a);
Effects:
Inserts a charT object.
Returns:
os << a
static bool is_del(char_type a);
Effects:
Characteristic function for delimiters of charT.
Returns:
isspace(a)
static int compare(const char_type* s1, const char_type* s2, size_t n);
Effects:
for (size_t i = 0; i < n; ++i, ++s1, ++s2)
if (ne(*s1, *s2))
return lt(*s1, *s2) ? -1 : 1;
return 0;
static size_t length(const char_type* s);
Effects:
size_t len = 0;
while (ne(*s++, eos())) ++len;
return len;
static char_type* copy(char_type* s1, const char_type* s2, size_t n);
Effects:
char_type* s = s1;
for (size_t i = 0; i < n; ++i) assign(*s1++, *s2++);
return s;
+------- BEGIN BOX 1 -------+
Here as elsewhere, this overconstrains implementations, in that there
is no particular reason to do the operations in the order specified.
+------- END BOX 1 -------+
21.1.1.3 Template class basic_string [lib.basic.string]
namespace std {
template<class charT, class traits = string_char_traits<charT>,
class Allocator = allocator>
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::types<charT>::reference reference;
typedef typename Allocator::types<charT>::const_reference const_reference;
typedef typename Allocator::types<charT>::pointer pointer;
typedef typename Allocator::types<charT>::const_pointer const_pointer;
typedef implementation_defined iterator;
typedef implementation_defined const_iterator;
typedef reverse_iterator<iterator, value_type,
reference, difference_type> reverse_iterator;
typedef reverse_iterator<const_iterator, value_type,
const_reference, difference_type> const_reverse_iterator;
static const size_type npos = -1;
// _lib.string.cons_ construct/copy/destroy:
explicit basic_string(const Allocator& = Allocator());
basic_string(const basic_string& str, size_type pos = 0,
size_type n = npos, const Allocator& = Allocator());
basic_string(const charT* s, size_type n, const Allocator& = Allocator());
basic_string(const charT* s, const Allocator& = Allocator());
basic_string(size_type n, charT c, const Allocator& = Allocator());
template<class InputIterator>
basic_string(InputIterator begin, InputIterator end,
const Allocator& = 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);
bool empty() const;
// _lib.string.access_ element access:
charT 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& rhs);
basic_string& operator+=(const charT* s);
basic_string& operator+=(charT c);
basic_string& append(const basic_string& str, size_type pos = 0,
size_type n = npos);
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& str, size_type pos = 0,
size_type n = npos);
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,
size_type pos2 = 0, size_type n = npos);
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& remove(size_type pos = 0, size_type n = npos);
basic_string& remove(iterator position);
basic_string& remove(iterator first, iterator last);
basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
size_type pos2 = 0, size_type n2 = npos);
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;
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,
size_type pos2 = 0, size_type n2 = npos) const;
int compare(const charT* s) const;
int compare(size_type pos1, size_type n1,
const charT* s, size_type n2 = npos const;
};
}
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. 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 a such given char-like type. Storage for the string is
allocated and freed as necessary by the member functions of class
basic_string.
2 In all cases, size() <= capacity().
3 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_).
21.1.1.4 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& = Allocator());
Effects:
Constructs an object of class basic_string. The postconditions of
this function are indicated in Table 2:
Table 2--basic_string() 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& = Allocator());
+------- BEGIN BOX 2 -------+
This is a copy constructor with an extra argument, so that it can be
used to copy a string while changing its allocator. Is this the best
way to do this?
+------- END BOX 2 -------+
Requires:
pos <= 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 3:
Table 3--basic_string(basic_string,size_type,size_type) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of rlen elements of |
| the string controlled by str begin |
| ning at position pos |
|size() rlen |
|capacity() a value at least as large as size() |
+-------------------------------------------------+
basic_string(const charT* s, size_type n,
const Allocator& = 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 n whose first
element is designated by s, as indicated in Table 4:
Table 4--basic_string(const charT*,size_type) 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& = 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 5:
Table 5--basic_string(const charT*) 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& = 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 6:
Table 6--basic_string(size_type,charT) 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& = Allocator());
Effects:
Constructs a string from the values in the range [begin, end), as
indicated in Table 7:
Table 7--basic_string(begin,end) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the elements in |
| the range [first,last) |
|size() distance between first and last |
|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 such that:
Table 7--operator=(str) effects
+-------------------------------------------------+
| Element Value |
+-------------------------------------------------+
|data() points at the first element of an |
| allocated copy of the the array |
| whose first element is pointed at |
| by str.size() |
|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).
21.1.1.5 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_iterator(end()).
reverse_iterator rend();
const_reverse_iterator rend() const;
Returns:
an iterator which is semantically equivalent to
reverse_iterator(begin()).
21.1.1.6 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 != npos
Throws:
length_error if n == npos.
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);
1 The member function reserve() is a directive that informs a
basic_string 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 if reallocation happens; and equal to the previous value of
capacity() otherwise.
Reallocation happens at this point if and only if the current capac
ity is less than the argument of reserve().
Complexity:
It does not change the size of the sequence and takes at most linear
time in the size of the sequence.
Notes:
Reallocation invalidates all the references, pointers, and iterators
referring to the elements in the sequence. It is guaranteed that no
reallocation takes place during the insertions that happen after
reserve() takes place till the time when the size of the string
reaches the size specified by reserve().
bool empty() const;
Returns:
size() == 0.
21.1.1.7 basic_string element access [lib.string.access]
charT operator[](size_type pos) const;
reference operator[](size_type pos);
Returns:
If pos < size(), returns data()[pos]. Otherwise, if pos == size(),
the const version returns traits::eos(). Otherwise, the behavior is
undefined.
Notes:
The reference returned by the non-const version is invalid after any
subsequent call to c_str(), data(), or any non-const member function
for the object.
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).
21.1.1.8 basic_string modifiers [lib.string.modifiers]
21.1.1.8.1 basic_string::operator+= [lib.string::op+=]
basic_string<charT,traits,Allocator>&
operator+=(const basic_string<charT,traits,Allocator>& rhs);
Returns:
append(rhs).
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).
21.1.1.8.2 basic_string::append [lib.string::append]
basic_string<charT,traits,Allocator>&
append(const basic_string<charT,traits>& str, size_type pos = 0,
size_type n = npos);
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)).
21.1.1.8.3 basic_string::assign [lib.string::assign]
basic_string<charT,traits,Allocator>&
assign(const basic_string<charT,traits>& str, size_type pos = 0,
size_type n = npos);
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(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)).
21.1.1.8.4 basic_string::insert [lib.string::insert]
basic_string<charT,traits,Allocator>&
insert(size_type pos1,
const basic_string<charT,traits,Allocator>& str,
size_type pos2 = 0, size_type n = npos);
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 referrred 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 referrred to by p.
21.1.1.8.5 basic_string::remove [lib.string::remove]
basic_string<charT,traits,Allocator>&
remove(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.
basic_string& remove(iterator p);
Requires:
p is a valid iterator on *this.
Effects:
removes the character referred to by p.
Returns:
*this.
basic_string& remove(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:
*this.
21.1.1.8.6 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,
size_type pos2 = 0, size_type n2 = npos);
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).
21.1.1.8.7 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.
Notes:
The function does not append a null object to the string.
Returns:
rlen.
21.1.1.8.8 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:
linear in general, constant if a.get_allocator() ==
b.get_allocator(). Constant time.
21.1.1.9 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.
const allocator_type& get_allocator() const;
Returns:
a reference to the string's allocator object.
21.1.1.9.1 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).
21.1.1.9.2 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).
21.1.1.9.3 [lib.string::find.first.of]
basic_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).
21.1.1.9.4 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).
21.1.1.9.5 [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).
21.1.1.9.6 [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).
21.1.1.9.7 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).
21.1.1.9.8 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 8:
Table 8--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,
size_type pos2 = 0, size_type n2 = npos) const
Returns:
basic_string<charT,traits,Allocator>(*this,pos1,n1).compare(
basic_string<charT,traist,Allocator>(str,pos2,n2))
int compare(charT *s) const;
Returns:
*this.compare(basic_string<charT,traits,Allocator>(s))
int compare(size_type pos, size_type n1,
chrT *s, size_type n2 = npos) const;
Returns:
basic_string<charT,traits,Allocator>(*this,pos,n1).compare(
basic_string<charT,traits,Allocator>(s,n2))
21.1.1.10 basic_string non-member [lib.string.nonmembers]
functions
21.1.1.10.1 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).
21.1.1.10.2 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().
21.1.1.10.3 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().
21.1.1.10.4 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).
21.1.1.10.5 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).
21.1.1.10.6 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).
21.1.1.10.7 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).
21.1.1.10.8 Inserters and extractors [lib.string.io]
template<class charT, class IS_traits,
class STR_traits, class STR_Alloc>
basic_istream<charT,IS_traits>&
operator>>(basic_istream<charT,IS_traits>& is,
basic_string<charT,STR_traits,STR_Alloc>& str);
Effects:
The function begins execuion by calling is.ipfx(true). If that
function returns true, the function endeavours to obtain the
requested input. The function extracts characters and appends then
to str as if by calling str.append(1,c). If is.width() is greater
than zero, the maximum number of characters stored is is.width();
otherwise it is str.max_size(). Characters are extracted and stored
until any of the following occurs:
--n characters are stored;
--end-of-file occurs on the input sequence;
--IS_traits::is_whitespace(c,ctype) is true for the next available
input character c, where ctype is acquired by calling
use_facet<ctype<charT> >(is.getloc()). In any case, the function
ends by calling is.isfx().
Returns:
is
template<class charT, class OS_traits,
class STR_traits, class STR_Alloc>
basic_ostream<charT, OS_traits>&
operator<<(basic_ostream<charT, OS_traits>& os,
const basic_string<charT,STR_traits,STR_Alloc>& str);
+------- BEGIN BOX 3 -------+
Change: Issue 21-008 in N0721R1=95-0121R1, approved in Monterey,
changed this to:
template<class charT, class IS_traits,
class STR_traits, class STR_Alloc>
basic_ostream<charT, IS_traits>&
operator<<(basic_istream<charT, OS_traits>& os,
basic_string<charT,STR_traits,STR_Alloc>& str);
This looks like a cut and paste error, and the above looks more rea
sonable. The declaration in 21.1 [lib.string.classes], which was not
in fact mentioned by the motion, has been corrected to match.
Steve Rumsby
+------- END BOX 3 -------+
Effects:
Behaves as if the function calls:
os.write(str.data(), str.size())
Returns:
os
template<class charT, class IS_traits, class STR_traits,
class STR_Alloc>
basic_istream<charT,IS_traits>&
getline(basic_istream<charT,IS_traits>& is,
basic_string<charT,STR_traits,STR_Alloc>& str,
charT delim = IS_traits::newline() );
Effects:
The function begins by callling is.ipfx(true). If that function
returns true, the function endeavours to extract the requested
input. It also counts the number of character extracted. The
string is initially made empty by calling str.remove(). Characters
are extracted from the stream and appended to the string as if by
calling str.append(1,c). Characters are extracted and appended
until one of the following occurs:
--end-of-file occurs on the input sequence (in which case, the func
tion 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.
2 In any case, the function ends by storing the count in is and calling
is.isfx(), then returning the value specified.
3 If the function extracts no characters, it calls
is.setstate(ios_base::failbit) which may throw ios_base::failure
(_lib.iostate.flags_).
Returns:
is.
Notes:
Uses STR_traits::char_in().
21.1.2 Class string [lib.string]
namespace std {
struct string_char_traits<char> {
typedef char char_type;
static void assign(char& c1, const char& c2);
static bool eq(const char& c1, const char& c2);
static bool ne(const char& c1, const char& c2);
static bool lt(const char& c1, const char& c2);
static char eos();
static basic_istream<char>& char_in (basic_istream<char>& is, char& a);
static basic_ostream<char>& char_out(basic_ostream<char>& os, char a);
static bool is_del(char a); // characteristic function for delimiters
static int compare(const char* s1, const char* s2, size_t n);
static size_type length(const char* s);
static char* copy(char* s1, const char* s2, size_t n);
};
typedef basic_string<char> string;
}
21.1.3 string_char_traits<char> [lib.string.traits.members]
members
static void assign(char& c1, const char& c2);
Effects:
c1 = c2.
static bool eq(const char& c1, const char& c2);
Returns:
c1 == c2.
static bool ne(const char& c1, const char& c2);
Returns:
c1 != c2.
static bool lt(const char& c1, const char& c2);
Returns:
c1 < c2.
static char eos();
Returns:
0.
basic_istream<char>& char_in (basic_istream<char>& is, char& a);
Returns:
is >> a .
basic_ostream<char>& char_out(basic_ostream<char>& os, char a);
Returns:
os << a.
bool is_del(char a);
Returns:
::isspace(a).
static int compare(const char* s1, const char* s2, size_t n);
Returns:
::memcmp(s1,s2,n).
static size_type length(const char* s);
Returns:
::strlen(s).
static char* copy(char* s1, const char* s2, size_t n);
Returns:
::memcpy(s1,s2,n).
21.1.4 Class wstring [lib.wstring]
namespace std {
struct string_char_traits<wchar_t> {
typedef wchar_t char_type;
static void assign(wchar_t& c1, const wchar_t& c2);
static bool eq(const wchar_t& c1, const wchar_t& c2);
static bool ne(const wchar_t& c1, const wchar_t& c2);
static bool lt(const wchar_t& c1, const wchar_t& c2);
static wchar_t eos();
static basic_istream<wchar_t>& char_in (basic_istream<wchar_t>& is, wchar_t& a);
static basic_ostream<wchar_t>& char_out(basic_ostream<wchar_t>& os, wchar_t a);
static bool is_del(wchar_t a); // characteristic function for delimiters
static int compare(const wchar_t* s1, const wchar_t* s2, size_t n);
static size_type length(const wchar_t* s);
static wchar_t* copy(wchar_t* s1, const wchar_t* s2, size_t n);
};
typedef basic_string<wchar_t> wstring;
}
21.1.5 string_char_traits<wchar_t> members [lib.wstring.members]
static void assign(wchar_t& c1, const wchar_t& c2);
Effects:
c1 = c2.
static bool eq(const wchar_t& c1, const wchar_t& c2);
Returns:
c1 == c2.
static bool ne(const wchar_t& c1, const wchar_t& c2);
Returns:
c1 != c2.
static bool lt(const wchar_t& c1, const wchar_t& c2);
Returns:
c1 < c2.
static wchar_t eos();
Returns:
0.
basic_istream<wchar_t>& char_in (basic_istream<wchar_t>& is, wchar_t& a);
Returns:
is >> a .
basic_ostream<wchar_t>& char_out(basic_ostream<wchar_t>& os, wchar_t a);
Returns:
os << a.
bool is_del(wchar_t a);
Returns:
::iswspace(a).
static int compare(const wchar_t* s1, const wchar_t* s2, size_t n);
Returns:
::wmemcmp(s1,s2,n).
static size_type length(const wchar_t* s);
Returns:
::wcslen(s).
static wchar_t* copy(wchar_t* s1, const wchar_t* s2, size_t n);
Returns:
::wmemcpy(s1,s2,n).
21.2 Null-terminated sequence utilities [lib.c.strings]
1 Headers <cctype>, <cwctype>, <cstring>, <cwchar>, <cstdlib> (multibyte
conversions), and <ciso646>.
Table 8--Header <cctype> synopsis
+-------------------------------------------------+
| Type Name(s) |
+-------------------------------------------------+
|Functions: |
|isalnum isdigit isprint isupper tolower |
|isalpha isgraph ispunct isxdigit toupper |
|iscntrl islower isspace |
+-------------------------------------------------+
Table 8--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 8--Header <cstring> synopsis
+-------------------------------------------------+
| Type Name(s) |
+-------------------------------------------------+
|Macro: NULL <cstring> |
+-------------------------------------------------+
|Type: size_t <cstring> |
+-------------------------------------------------+
|Functions: |
|strcoll strlen strpbrk strtok |
|strcat strcpy strncat strrchr strxfrm |
|strchr strcspn strncmp strspn |
|strcmp strerror strncpy strstr |
+-------------------------------------------------+
Table 8--Header <cwchar> synopsis
+------------------------------------------------------------------------+
| Type Name(s) |
+------------------------------------------------------------------------+
|Macros: NULL <cwchar> WCHAR_MAX WCHAR_MIN WEOF <cwchar> |
+------------------------------------------------------------------------+
|Types: mbstate_t wint_t <cwchar> |
+------------------------------------------------------------------------+
|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 8--Header <cstdlib> synopsis
+-----------------------------------------+
| Type Name(s) |
+-----------------------------------------+
|Macros: MB_CUR_MAX |
+-----------------------------------------+
|Functions: |
|atol mblen strtod wctomb |
|atof mbstowcs strtol wcstombs |
|atoi mbtowc stroul |
+-----------------------------------------+
2 The contents are the same as the Standard C library, with the follow
ing 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_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.