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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.
NAME
ctype.h — character types
SYNOPSIS
#include <ctype.h>
DESCRIPTION
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.1‐2008, 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
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
<locale.h>
The System Interfaces volume of POSIX.1‐2008, 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()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .