NAME

isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii − classify characters

SYNOPSIS

#include <ctype.h>

int isalpha (c)
int c;

. . . 

DESCRIPTION

These macros classify character-coded integer values according to the rules of the coded character set identified by the last successful call to nl_init(3C). Each macro is a predicate returning non-zero for true, zero for false.

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

Isascii is defined on all integer values; the other macros are defined for the range −1 (EOF) to 255. 

isalpha c is a letter. 

isupper c is an uppercase letter. 

islower c is a lowercase letter. 

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

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

isalnum c is an alphanumeric (letters or digits). 

isspace c is a character that creates "white space" in displayed text (in ASCII:  space, tab, carriage return, new-line, vertical tab, and form-feed). 

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

isprint c is a printing character. 

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

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

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

DIAGNOSTICS

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

AUTHOR

Ctype was developed by AT&T and HP. 

DEPENDENCIES

Series 300, 500
Characters are classified according to the rules of the default ASCII 7-bit coded character set because nl_init(3C) is not currently supported. For NLS, use the routines described in nl_ctype(3C) instead.

SEE ALSO

nl_init(3C), stdio(3S), ascii(5). 

INTERNATIONAL SUPPORT

8-bit data. 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021