malloc_usable_size - obtain size of block of memory allocated from heap
#include <malloc.h>
size_t malloc_usable_size (void *ptr);
The
malloc_usable_size() function returns the number of usable bytes in
the block pointed to by
ptr, a pointer to a block of memory allocated
by
malloc(3) or a related function.
malloc_usable_size() returns the number of usable bytes in the block of
allocated memory pointed to by
ptr. If
ptr is NULL, 0 is
returned.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| malloc_usable_size () |
Thread safety |
MT-Safe |
This function is a GNU extension.
The value returned by
malloc_usable_size() may be greater than the
requested size of the allocation because of alignment and minimum size
constraints. Although the excess bytes can be overwritten by the application
without ill effects, this is not good programming practice: the number of
excess bytes in an allocation depends on the underlying implementation.
The main use of this function is for debugging and introspection.
malloc(3)