FWIDE(3P)

💖 PROLOG 💖

okay so bestie, real talk first: this whole page is part of the POSIX Programmer's Manual (yes the whole thing, it's a volume). The Linux version of this interface might act different from what's written here — so if you're on Linux, go peek at the matching Linux manual page for the deets on Linux behavior. Or honestly? The interface might not even be implemented on Linux at all. 🙈 vibe check accordingly.

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✨ NAME ✨

fwide — set stream orientation 🦋 (yes that's the whole name, it's giving "short and iconic")

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🌸 SYNOPSIS 🌸

#include <stdio.h>
#include <wchar.h>

int fwide(FILE *stream, int mode);

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💅 DESCRIPTION 💅

So the functionality on this reference page is aligned with the ISO C standard, periodt. And if there's any conflict between what's written here and the ISO C standard? That conflict is unintentional, no cap. This volume of POSIX.1‐2017 literally defers to the ISO C standard. 👑

The fwide() function shall determine the orientation of the stream pointed to by stream. Here's the tea on mode:

• if mode is greater than zero, the function first attempts to make the stream wide-oriented ✨
• if mode is less than zero, the function first attempts to make the stream byte-oriented 🍓
• otherwise, mode is zero and the function does not alter the orientation of the stream — it just vibes and observes 👀

If the orientation of the stream has already been determined, fwide() shall not change it. It's locked in, bestie, that's just how it is. 🔒

Also — and this is lowkey important — the fwide() function shall not change the setting of errno if successful.

and because no return value is reserved to indicate an error, if you're an application wishing to check for error situations you should: set errno to 0, then call fwide(), then check errno, and if it is non-zero, assume an error has occurred. that's the whole ritual, no shortcuts. 😭

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🎀 RETURN VALUE 🎀

The fwide() function shall return:

• a value greater than zero if, after the call, the stream has wide-orientation 🔥
• a value less than zero if the stream has byte-orientation 🌈
• zero if the stream has no orientation 💀

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⭐ ERRORS ⭐

The fwide() function may fail if:

• EBADF — the stream argument is not a valid stream. 🚫 (yeah, that stream is not it)

heads up: the following sections are informative. (translation: cute bonus lore, not rules)

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🧚 EXAMPLES 🧚

None. 💅 nothing to show, the function simply exists.

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💜 APPLICATION USAGE 💜

A call to fwide() with mode set to zero can be used to determine the current orientation of a stream. That's the move — don't change anything, just ask. 🫶

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🌟 RATIONALE 🌟

None.

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🦋 FUTURE DIRECTIONS 🦋

None.

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👑 SEE ALSO 👑

The Base Definitions volume of POSIX.1‐2017, <stdio.h>, <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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and that's the whole page, bestie!! 🎀 brought to you by IEEE/The Open Group, dated 2017, and it's literally the FWIDE(3P) page from the POSIX Programmer's Manual — go forth and set those stream orientations, you main character 💅✨