ctype.h(0P)

💖 ctype.h — character types 💖

okay bestie, welcome to the POSIX Programmer's Manual page for ctype.h(0P) 🎀 — yes this is the real one, and yes I'm gonna walk you through the whole thing like we're texting at 2am.

🫶 heads up though: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go check the corresponding Linux manual page for the deets on Linux behavior, fr), or honestly the interface may not even be implemented on Linux at all. 💀

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✨ NAME ✨

ctype.h — character types 🌸

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✨ SYNOPSIS ✨

#include <ctype.h>

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✨ DESCRIPTION ✨

so some of the functionality on this reference page extends the ISO C standard — meaning it goes above and beyond, main character energy 👑. For that extended stuff, applications shall define the appropriate feature test macro (see the System Interfaces volume of POSIX.1‐2017, Section 2.2, The Compilation Environment) to enable the visibility of these symbols in this header. iykyk. 🦋

The <ctype.h> header shall define the locale_t type as described in <locale.h>, representing a locale object. (yes, a whole locale, as a treat ✨)

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided for use with ISO C standard compilers. 💅

int   isalnum(int);
int   isalnum_l(int, locale_t);
int   isalpha(int);
int   isalpha_l(int, locale_t);
int   isascii(int);
int   isblank(int);
int   isblank_l(int, locale_t);
int   iscntrl(int);
int   iscntrl_l(int, locale_t);
int   isdigit(int);
int   isdigit_l(int, locale_t);
int   isgraph(int);
int   isgraph_l(int, locale_t);
int   islower(int);
int   islower_l(int, locale_t);
int   isprint(int);
int   isprint_l(int, locale_t);
int   ispunct(int);
int   ispunct_l(int, locale_t);
int   isspace(int);
int   isspace_l(int, locale_t);
int   isupper(int);
int   isupper_l(int, locale_t);
int   isxdigit(int);
int   isxdigit_l(int, locale_t);
int   toascii(int);
int   tolower(int);
int   tolower_l(int, locale_t);
int   toupper(int);
int   toupper_l(int, locale_t);

The <ctype.h> header shall define the following as macros 🎀:

int   _toupper(int);
int   _tolower(int);

The following sections are informative. (aka, the bonus lore 🌈)

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✨ APPLICATION USAGE ✨

None. literally nothing. iconic behavior, honestly 😌

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✨ RATIONALE ✨

None. again! the void! we stan a minimalist 💜

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✨ FUTURE DIRECTIONS ✨

None. the future is... also nothing. slay 🌟

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✨ SEE ALSO ✨

• <locale.h>

and also, from the System Interfaces volume of POSIX.1‐2017:

• Section 2.2, The Compilation Environment
• isalnum(), isalpha(), isascii(), isblank(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit(), mblen(), mbstowcs(), mbtowc(), setlocale(), toascii(), tolower(), _tolower(), toupper(), _toupper(), wcstombs(), wctomb()

go read those too bestie, they're all connected 🦋✨

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✨ COPYRIGHT ✨

okay legal moment, but make it cute 💅

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, no cap, every last option and prototype accounted for. IEEE/The Open Group, 2017 — ctype.h(0P) out. mwah 💋🌸