_TOUPPER(3POSIX)

💖 _TOUPPER — the POSIX Programmer's Manual glow-up 💖

okay bestie, so this one lives in the POSIX Programmer's Manual — that's the manual name, and the page itself is _TOUPPER(3POSIX). buckle up, it's a tiny page but it's got lore 🎀

---

🚨 PROLOG 🚨

so first thing's first, the fine print, and it's giving "read me before you @ me":

• This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so pls consult the corresponding Linux manual page for details on Linux behavior — or the interface might not even be implemented on Linux at all. 💀

like, it might just not exist for you. vibe check your platform first, fr fr.

---

✨ NAME ✨

_toupper — transliterate lowercase characters to uppercase 👑

---

🌸 SYNOPSIS 🌸

#include <ctype.h>

int _toupper(int c);

there it is. one include, one macro, no drama.

---

💅 DESCRIPTION 💅

okay so here's the whole deal: _toupper() shall be equivalent to toupper() — same energy, same behavior — except that the application shall ensure that the argument c is a lowercase letter.

read that again. the application has to guarantee it. that's on you, not on the macro. it's giving "trust me bro" but the bro is you 😭

---

🔥 RETURN VALUE 🔥

upon successful completion, _toupper() shall return the uppercase letter corresponding to the argument you passed in. that's it. that's the whole return value. slay.

---

💀 ERRORS 💀

No errors are defined.

nope, nothing, zero, zilch — there is no error list here to check, bestie. don't go looking.

The following sections are informative. (iykyk — informative means "for your enrichment", not "normative, you must obey".) 📚

---

🙈 EXAMPLES 🙈

None.

literally none. the page said "no examples, figure it out" and honestly? iconic behavior.

---

🫶 APPLICATION USAGE 🫶

applications should use the toupper() function instead of the obsolescent _toupper() function.

so like, _toupper() is lowkey a relic. the word is obsolescent. use toupper(), bestie, please, for me 🥺

---

🌈 RATIONALE 🌈

None.

no reasoning provided. no thoughts, head empty, just vibes.

---

⭐ FUTURE DIRECTIONS ⭐

The _toupper() function may be removed in a future version.

🚨 this is your warning arc. it's on the chopping block. don't build your whole personality around it. if you're writing new code, this is not the main character — pick toupper().

---

🦋 SEE ALSO 🦋

• islower()
• toupper()

and also, from the Base Definitions volume of POSIX.1‐2017:

• Chapter 7, Locale
• <ctype.h>

---

👑 COPYRIGHT 👑

okay the boring-but-mandatory section, but we're gonna read it with respect because it's literally the receipts:

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 .

---

and that's the whole page, bestie!! 💖 it's short, it's sweet, it's obsolescent, and it's brought to you by IEEE/The Open Group, 2017 — that's the source, the version, and the date, all wrapped up in one little sign-off. mwah, go use toupper() 💅✨🎀