WCSTOMBS(3P)

💖 WCSTOMBS(3P) 💖

ok bestie, so this one lives in the POSIX Programmer's Manual (that's the 3P situation, iykyk) 💅

✨ PROLOG ✨

Heads up before we even start: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so if you're on Linux, go consult the corresponding Linux manual page for the deets on Linux behavior. Orrr the interface might not even be implemented on Linux at all. Not me warning you first thing 🫶

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🎀 NAME 🎀

wcstombs — convert a wide-character string to a character string

that's it that's the whole job, she converts, she slays ✨

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🌸 SYNOPSIS 🌸

#include <stdlib.h>

size_t wcstombs(char *restrict s, const wchar_t *restrict pwcs,
    size_t n);

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💜 DESCRIPTION 💜

So real talk: the functionality on this reference page is aligned with the ISO C standard. If anything here conflicts with the ISO C standard, that's unintentional, bestie — and this volume of POSIX.1-2017 defers to the ISO C standard. Periodt.

wcstombs() shall convert the sequence of wide-character codes sitting in the array pointed to by pwcs into a sequence of characters that begins in the initial shift state, and store those characters into the array pointed to by s. She stops if:

• a character would exceed the limit of n total bytes, or
• a null byte is stored.

Each wide-character code shall be converted as if by a call to wctomb(), EXCEPT that the shift state of wctomb() shall not be affected. no side-eye on the shift state, we leave it alone 💅

The behavior of this function shall be affected by the LC_CTYPE category of the current locale. (locale girlies stay winning)

No more than n bytes shall be modified in the array pointed to by s.

Also, if copying takes place between objects that overlap, the behavior is undefined. 🚨 do NOT do the overlapping thing, it's giving chaos 🚨

And if s is a null pointer, wcstombs() shall return the length required to convert the entire array regardless of the value of n, but no values are stored. she's just doing math for you at that point, no writing, just vibes ✨

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💚 RETURN VALUE 💚

If a wide-character code is encountered that does not correspond to a valid character (of one or more bytes each), wcstombs() shall return (size_t)-1. oof 💀

Otherwise, wcstombs() shall return the number of bytes stored in the character array, not including any terminating null byte.

And lowkey important: the array shall not be null-terminated if the value returned is n. remember that, it's a trap fr fr 🙈

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🧡 ERRORS 🧡

The wcstombs() function shall fail if:

• EILSEQ — A wide-character code does not correspond to a valid character.

the following sections are informative, bestie — so it's bonus lore, not rules 📖

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🦋 EXAMPLES 🦋

None. (nothing to see here, moving on 💅)

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🌈 APPLICATION USAGE 🌈

None. iconic, no notes 🫶

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💖 RATIONALE 💖

None.

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⭐ FUTURE DIRECTIONS ⭐

None.

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👑 SEE ALSO 👑

• mblen()
• mbtowc()
• mbstowcs()
• wctomb()

Also the Base Definitions volume of POSIX.1-2017, <stdlib.h> 📚

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🍓 COPYRIGHT 🍓

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 bestie 💖✨ go convert some wide chars, you've got this 🎀🦋🌸💅🫶

this cutie was brought to you by IEEE/The Open Group, dated 2017 — mwah 💋