ctype.h - Man Page

character types


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <ctype.h>


Some of the functionality described on this reference page extends the ISO C standard. 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.

The <ctype.h> header shall define the locale_t type as described in <locale.h>, representing a locale object.

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.

Application Usage




Future Directions


See Also


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()

Referenced By

isalnum(3p), isalpha(3p), isascii(3p), isblank(3p), iscntrl(3p), isdigit(3p), isgraph(3p), islower(3p), isprint(3p), ispunct(3p), isspace(3p), isupper(3p), isxdigit(3p), toascii(3p), _tolower(3p), tolower(3p), _toupper(3p), toupper(3p), wchar.h(0p), wctype.h(0p).

2017 IEEE/The Open Group POSIX Programmer's Manual