NAME

isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, toupper, tolower − character classification macros

SYNOPSIS

#include <ctype.h>

isalpha(int c);

. . . 

DESCRIPTION

These interfaces classify C locale integer values by table lookup.  Each is a predicate returning nonzero for true, zero for false. 

isalpha c is a letter

isupper c is an upper case letter

islower c is a lower case letter

isdigit c is a digit

isxdigit c is a hex digit

isalnum c is any character for which isalpha or isdigit is true. 

isspace c is a space, tab, carriage return, newline, vertical tab, or formfeed

ispunct c is a punctuation character (neither control nor alphanumeric)

isprint c is a printing character, code 040(8) (space) through 0176 (tilde)

isgraph c is a printing character, similar to isprint except false for space. 

iscntrl c is a delete character (0177) or ordinary control character (less than 040). 

tolower c is converted to lower case.  Return value is undefined if not isupper(c). 

toupper c is converted to upper case.  Return value is undefined if not islower(c). 

NOTE

These interfaces are provided in the form of macros and functions. 

If you’re using NEXTSTEP font encoding, then you shouldn’t use these interfaces; use the NXCType functions instead.  NXCType is discussed in the online NEXTSTEP documentation (accessible through the Digital Librarian).  These macros are provided to support ANSI-C. 

SEE ALSO

ascii(7), online NEXTSTEP documentation for NXCType

7th Edition  —  August 1, 1992