The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### 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 the System Interfaces volume of IEEE Std 1003.1-2001, Section 2.2, The Compilation Environment) to enable the visibility of these symbols in this header.

> The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

>     int   isalnum(int);
>     int   isalpha(int);
>     [XSI]
>     int   isascii(int);

>     int   isblank(int);
>     int   iscntrl(int);
>     int   isdigit(int);
>     int   isgraph(int);
>     int   islower(int);
>     int   isprint(int);
>     int   ispunct(int);
>     int   isspace(int);
>     int   isupper(int);
>     int   isxdigit(int);
>     [XSI]
>     int   toascii(int);

>     int   tolower(int);
>     int   toupper(int);

> The following are defined as macros:

>     [XSI]
>     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 IEEE Std 1003.1-2001, isalnum(), isalpha(), isascii(), 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.

End of informative text.

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