term% cat index.txt CTYPE(3) Library Functions Manual CTYPE(3)
NAME
isalpha, isupper, islower, isdigit, isalnum, isspace, ispunct, isprint,
iscntrl, isascii - character classification
SYNOPSIS
#include <ctype.h>
isalpha(c)
. . .
DESCRIPTION
These macros classify ASCII-coded integer values by table lookup. Each
is a predicate returning nonzero for true, zero for false. Isascii is
defined on all integer values; the rest are defined only where isascii
is true and on the single non-ASCII value EOF (see stdio(3)).
isalpha c is a letter
isupper c is an upper case letter
islower c is a lower case letter
isdigit c is a digit
isalnum c is an alphanumeric character
isspace c is a space, tab, carriage return, newline, or formfeed
ispunct c is a punctuation character (neither control nor al‐
phanumeric)
isprint c is a printing character, code 040(8) (space) through
0176 (tilde)
iscntrl c is a delete character (0177) or ordinary control char‐
acter (less than 040).
isascii c is an ASCII character, code less than 0200
SEE ALSO
ascii(7)
CTYPE(3)