Issue 0075: What is the alignment of allocated memory?

This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.

Authors: Clive Feather, WG14
Date: 1993-12-03
Submitted against: C90
Status: Closed
Converted from: dr.htm, dr_075.html

Item 12 - alignment of allocated memory

Is a piece of memory allocated by malloc required to be aligned suitably for any type, or only for those types that will fit into the space? For example, following the assignment:

void *vp = malloc (1);

is it required that (void *)(int *)vp compare equal to vp (assuming that sizeof(int) > 1), or is it permissible for vp to be a value not suitably aligned to point to an int?

Comment from WG14 on 1997-09-23:

Response

Subclause 7.10.3 requires allocated memory to be suitably aligned for any type, so they must compare equal.