The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> ctype.h - character types

#### SYNOPSIS

> `#include <ctype.h>`

#### DESCRIPTION

> [CX] Some of the functionality described on this reference page extends the ISO C standard. Applications shall define the appropriate feature test macro (see XSH 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);
>     [CX]
>     int   isalnum_l(int, locale_t);

>     int   isalpha(int);
>     [CX]
>     int   isalpha_l(int, locale_t);

>     [OB XSI]
>     int   isascii(int);

>     int   isblank(int);
>     [CX]
>     int   isblank_l(int, locale_t);

>     int   iscntrl(int);
>     [CX]
>     int   iscntrl_l(int, locale_t);

>     int   isdigit(int);
>     [CX]
>     int   isdigit_l(int, locale_t);

>     int   isgraph(int);
>     [CX]
>     int   isgraph_l(int, locale_t);

>     int   islower(int);
>     [CX]
>     int   islower_l(int, locale_t);

>     int   isprint(int);
>     [CX]
>     int   isprint_l(int, locale_t);

>     int   ispunct(int);
>     [CX]
>     int   ispunct_l(int, locale_t);

>     int   isspace(int);
>     [CX]
>     int   isspace_l(int, locale_t);

>     int   isupper(int);
>     [CX]
>     int   isupper_l(int, locale_t);

>     int   isxdigit(int);
>     [CX]
>     int   isxdigit_l(int, locale_t);

>     [OB XSI]
>     int   toascii(int);

>     int   tolower(int);
>     [CX]
>     int   tolower_l(int, locale_t);

>     int   toupper(int);
>     [CX]
>     int   toupper_l(int, locale_t);

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

>     [OB XSI]
>     int   _toupper(int);
>     int   _tolower(int);

The following sections are informative.

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> <locale.h>

> XSH 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

#### CHANGE HISTORY

> First released in Issue 1. Derived from Issue 1 of the SVID.

#### Issue 6

> Extensions beyond the ISO C standard are marked.

#### Issue 7

> SD5-XBD-ERN-6 is applied, updating the wording regarding the function declarations for consistency.

> The *_l() functions are added from The Open Group Technical Standard, 2006, Extended API Set Part 4.

End of informative text.

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