CTYPE(3P)CTYPE(3P)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 ALSOascii(7), online NEXTSTEP documentation for NXCType
7th Edition August 1, 1992 CTYPE(3P)