FREE(3P) POSIX Programmer's Manual FREE(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
free — free allocated memory
void free(void *ptr);
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here
and the ISO C standard is unintentional. This volume of POSIX.1‐2008
defers to the ISO C standard.
The free() function shall cause the space pointed to by ptr to be deal‐
located; 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 a function in POSIX.1‐2008 that
allocates memory as if by malloc(), or if the space has been deallo‐
cated 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>.
SEE ALSOcalloc(), malloc(), posix_memalign(), realloc()
The Base Definitions volume of POSIX.1‐2008, <stdlib.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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 http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
IEEE/The Open Group 2013 FREE(3P)