WCRTOMB(3P)

💖 WCRTOMB(3P) — POSIX Programmer's Manual 💖

okay bestie, welcome to wcrtomb(3P), a page from the POSIX Programmer's Manual (3P section, we love a P) 🎀

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✨ PROLOG ✨

so this manual page is part of the POSIX Programmer's Manual, right? but heads up — the Linux implementation of this interface may differ, so you should go consult the corresponding Linux manual page for the deets on Linux behavior. or like… the interface might not even be implemented on Linux at all. 🙈 vibe check your platform first, fr fr.

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👑 NAME 👑

wcrtomb — convert a wide-character code to a character (restartable)

like. it's giving "wide char → multibyte char, but make it resumable." 💅

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🌸 SYNOPSIS 🌸

#include <wchar.h>

size_t wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict ps);

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🦋 DESCRIPTION 🦋

okay so first things first: the functionality described on this reference page is aligned with the ISO C standard. and if there's any conflict between the requirements described here and the ISO C standard, that conflict is unintentional — no drama intended. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

If s is a null pointer, the wcrtomb() function shall be equivalent to the call:

wcrtomb(buf, L'\0', ps)

where buf is an internal buffer. (yes, an internal buffer, she's private like that ✨)

If s is not a null pointer, wcrtomb() shall determine the number of bytes needed to represent the character that corresponds to the wide character given by wc — including any shift sequences, don't forget those bestie — and store the resulting bytes in the array whose first element is pointed to by s. At most {MB_CUR_MAX} bytes are stored. If wc is a null wide character, a null byte shall be stored, preceded by any shift sequence needed to restore the initial shift state. And the resulting state described shall be the initial conversion state. we love a reset moment 💖

If ps is a null pointer, the wcrtomb() function shall use its own internal mbstate_t object, which is initialized at program start-up to the initial conversion state. Otherwise, the mbstate_t object pointed to by ps shall be used to completely describe the current conversion state of the associated character sequence. And — important — the implementation shall behave as if no function defined in this volume of POSIX.1‐2017 calls wcrtomb(). like, nobody else is touching her, okay? 🫶

⚠️ The wcrtomb() function need not be thread-safe if called with a NULL ps argument. so if you're threading, pass your own ps, iykyk.

The behavior of this function shall be affected by the LC_CTYPE category of the current locale. 🌈

And the wcrtomb() function shall not change the setting of errno if successful. she's polite like that.

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💀 RETURN VALUE 💀

The wcrtomb() function shall return the number of bytes stored in the array object (including any shift sequences). 🎀

When wc is not a valid wide character, an encoding error shall occur. In this case, the function shall store the value of the macro [EILSEQ] in errno and shall return (size_t)-1; the conversion state shall be undefined. yeah. undefined. we do not know her. 😭

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🔥 ERRORS 🔥

The wcrtomb() function shall fail if:

• EILSEQ — An invalid wide-character code is detected.

The wcrtomb() function may fail if:

• EINVAL — ps points to an object that contains an invalid conversion state.

📌 The following sections are informative.

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🌟 EXAMPLES 🌟

None.

(she said "no examples, figure it out" 💅)

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🧚 APPLICATION USAGE 🧚

None.

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💜 RATIONALE 💜

None.

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⭐ FUTURE DIRECTIONS ⭐

None.

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🌈 SEE ALSO 🌈

• mbsinit()
• wcsrtombs()

The Base Definitions volume of POSIX.1‐2017, <wchar.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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okay that's the whole thing, bestie, you ate that 🫶 this lil love letter was brought to you by IEEE/The Open Group, 2017, and it lives in the WCRTOMB(3P) era of your life. mwah 💖✨