FREE(3POSIX)

💖 FREE(3POSIX) 💖

okay bestie, gather round, we're talking about free from the POSIX Programmer's Manual — she's iconic, she's tiny, and she is so important. let's get into it 🫶

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✨ PROLOG ✨

okay so real talk first, this is the disclaimer era:

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.

like… yes girl, check your local Linux page too, don't come for me 🌸

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🎀 NAME 🎀

free — free allocated memory

she does exactly what it says on the tin. no notes. 💅

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🌈 SYNOPSIS 🌈

#include <stdlib.h>

void free(void *ptr);

that's it. that's the whole vibe. one function, one pointer, endless power 👑

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🦋 DESCRIPTION 🦋

okay so, housekeeping first: 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. (translation: if the ISO C girlies say something different, they win, no drama 💖)

now the actual tea ☕:

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. (chill. it's fine. nothing happens. she's unbothered 😌)

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 deallocated by a call to free() or realloc(), the behavior is undefined.

🚨 bestie this is the important part 🚨 undefined behavior means the universe makes no promises. don't double free. don't free a pointer you got from anywhere sketchy. don't free the same thing twice. it's giving chaos and chaos is not cute here 😭

and one more, for the road:

Any use of a pointer that refers to freed space results in undefined behavior.

so once she's freed, she's gone. no peeking. no touching. we don't use stale pointers in this house 🙈

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⭐ RETURN VALUE ⭐

The free() function shall not return a value.

not void as in "returns nothing interesting" — void as in there is literally nothing to return. don't try to catch it, there's nothing to catch 💀

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💜 ERRORS 💜

No errors are defined.

The following sections are informative.

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🍓 EXAMPLES 🍓

None.

(yeah. none. she's too iconic to need a demo. iykyk 😌✨)

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🌸 APPLICATION USAGE 🌸

There is now no requirement for the implementation to support the inclusion of <malloc.h>.

so if you're out here #include <malloc.h> for no reason… bestie. use <stdlib.h>. it's giving 1990s. we've moved on 💅

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🧚 RATIONALE 🧚

None.

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💫 FUTURE DIRECTIONS 💫

None.

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👑 SEE ALSO 👑

• calloc()
• malloc()
• posix_memalign()
• realloc()

The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

the whole memory-allocation friend group, honestly. they all hang out. you should go read them next 🌈

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📜 COPYRIGHT 📜

okay legal besties, here's the fine print, don't skip it, she's real:

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 http://www.opengroup.org/unix/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.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page, babe 🫶 courtesy of IEEE/The Open Group, 2017 — FREE(3POSIX), periodt 💖✨🎀

now go free your memory properly, bestie. and only once. mwah 💋