TOLOWER(3P)

🎀 TOLOWER(3P) 🎀

okay bestie, welcome to the POSIX Programmer's Manual 💖 this is the tolower page and she is lowkey iconic. quick heads up before we dive in:

PROLOG

so like, this manual page is part of the POSIX Programmer's Manual. the Linux implementation of this interface may differ (bestie, go check the corresponding Linux manual page for the deets on Linux behavior), or honestly the interface may not even be implemented on Linux. no cap. 🙈

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NAME

tolower, tolower_l — transliterate uppercase characters to lowercase ✨

it's giving "make the big letters small." the way that's literally the whole job. 💅

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SYNOPSIS

#include <ctype.h>

int tolower(int c);
int tolower_l(int c, locale_t locale);

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DESCRIPTION

okay so for tolower(): 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 — nobody's trying to start drama. this volume of POSIX.1‐2017 defers to the ISO C standard. periodt. 👑

the tolower() and tolower_l() functions have as a domain a type int, the value of which is representable as an unsigned char or the value of EOF. 🫶 if the argument has any other value, the behavior is undefined — so like, don't do that, fr fr. that's not a vibe, that's a crash waiting to happen. 💀

if the argument of tolower() or tolower_l() represents an uppercase letter, and there exists a corresponding lowercase letter as defined by character type information in the current locale or in the locale represented by locale, respectively (category LC_CTYPE), the result shall be the corresponding lowercase letter. all other arguments in the domain are returned unchanged. she's not gonna mess with stuff that isn't her business. 🌸

⚠️ the behavior is undefined if the locale argument to tolower_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle. do NOT come for her with a fake locale, she will not know what to do and that's on undefined behavior bestie 😭

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RETURN VALUE

upon successful completion, the tolower() and tolower_l() functions shall return the lowercase letter corresponding to the argument passed; otherwise, they shall return the argument unchanged. so like: cute letter in, cute letter out; weird letter in, same weird letter out. no notes. 💜

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ERRORS

no errors are defined. she simply does not have problems. ✨

the following sections are informative.

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EXAMPLES

none. 🙈 (not me leaving you with zero examples, i know, i know — but that's literally what the page says, so we're keeping it real.)

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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

• setlocale()
• uselocale()

and also, from the Base Definitions volume of POSIX.1‐2017: Chapter 7, Locale, <ctype.h>, <locale.h> 📚

iykyk — if you're messing with locales you're gonna want those two functions up there. go read them, bestie, they're the main characters of this whole locale situation. 💖

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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 page, you ate that 🫶 this was IEEE/The Open Group, 2017, signing off like the absolute icon she is. go lowercase something cute. mwah 💅👑🌸