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ctype(3C)

HP-UX 11i Version 3: February 2007
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NAME

ctype: isalnum(), isalpha(), isascii(), isblank(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit() — classify characters according to type

SYNOPSIS

#include <ctype.h>

int isalnum(int c); int isalpha(int c); int isascii(int c); int isblank(int c); int iscntrl(int c); int isdigit(int c); int isgraph(int c); int islower(int c); int isprint(int c); int ispunct(int c); int isspace(int c); int isupper(int c); int isxdigit(int c);

DESCRIPTION

These functions classify character-coded integer values according to the rules of the coded character set identified by the last successful call to setlocale() (see setlocale(3C)). Each function is a predicate returning nonzero for true, zero for false.

If setlocale() has not been called successfully, characters are classified according to the rules of the default ASCII 7-bit coded character set (see setlocale(3C)).

isascii() is defined on all integer values; the other functions are defined for the range -1 (EOF) through 255.

RETURN VALUE

The functions return nonzero under the following circumstances; zero otherwise:

isalnum(c)

c is an alphanumeric (letters or digits).

isalpha(c)

c is a letter.

isascii(c)

c is any ASCII character code between 0 and 0177, inclusive.

isblank(c)

c is a blank character; that is, a space or a tab.

iscntrl(c)

c is a control character (in ASCII: character codes less than 040 and the delete character (0177)).

isdigit(c)

c is a decimal digit (in ASCII: characters [0-9]).

isgraph(c)

c is a visible character (in ASCII: printing characters, excluding the space character (040)).

islower(c)

c is a lowercase letter.

isprint(c)

c is a printing character.

ispunct(c)

c is a punctuation character (in ASCII: any printing character except the space character (040), digits, letters).

isspace(c)

c is a character that creates whitespace in displayed text (in ASCII: space, tab, carriage return, newline, vertical tab, and formfeed).

isupper(c)

c is an uppercase letter.

isxdigit(c)

c is a hexadecimal digit (in ASCII: characters [0-9], [A-F] or [a-f]).

If the argument to any of these functions is outside the domain of the function, the result is undefined.

EXTERNAL INFLUENCES

Environment Variables

The LC_CTYPE category determines the classification of character type.

International Code Set Support

Single-byte character code sets are supported.

WARNINGS

These functions are supplied both as library functions and as macros defined in the <ctype.h> header. Normally, the macro versions are used. To obtain the library function, either use a #undef to remove the macro definition or, if compiling in ANSI-C mode, enclose the function name in parenthesis or take its address. The following example uses the library functions for isalpha(), isdigit(), and isspace():

#include <ctype.h> #undef isalpha ... main() { int (*ctype_func)(); ... if ( isalpha(c) ) ... if ( (isdigit)(c) ) ... ctype_func = isspace; ... }

AUTHOR

ctype() was developed by IBM, OSF, and HP.

STANDARDS CONFORMANCE

isalnum(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isalpha(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isascii(): AES, SVID2, SVID3, XPG2, XPG3, XPG4

isblank(): ISO/IEC 9899:1999 (C99), UNIX 03

iscntrl(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isdigit(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isgraph(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

islower(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isprint(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

ispunct(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isspace(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isupper(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

isxdigit(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, ANSI C

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