The free() function shall cause the space pointed to by ptr
to be deallocated; that is, made available for further
allocation. If ptr is a null pointer, no action shall occur.
Otherwise, if the argument does not match a pointer earlier
returned by the calloc(), malloc(),
posix_memalign(), realloc(), or strdup() function,
or if the space has been deallocated by a call to free() or
realloc(), the behavior is undefined.
Any use of a pointer that refers to freed space results in undefined
The free() function shall not return a value.
No errors are defined.
The following sections are informative.
There is now no requirement for the implementation to support the
inclusion of <malloc.h>.
calloc() , malloc() , realloc() , the Base Definitions
volume of IEEE Std 1003.1-2001, <stdlib.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at