Section: POSIX Programmer's Manual (3P)
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 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.1-2017 defers to the ISO C standard.
function shall cause the space pointed to by
to be deallocated; that is, made available for further allocation. If
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
or if the space has been deallocated by a call to
the behavior is undefined.
Any use of a pointer that refers to freed space results in undefined
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
The Base Definitions volume of POSIX.1-2017,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 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
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