ctype(3c)
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isalpha, isupper, islower, isdigit, isxdigit, isalnum,
isspace, ispunct, isprint, isgraph, iscntrl, isascii
classify characters
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SYNTAX
#include <ctype.h> int isalpha (c) int c; . . .
DESCRIPTION
These macros classify character-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(3S)).
isalpha c is a letter.
isupper c is an uppercase letter.
islower c is a lowercase letter.
isdigit c is a digit [0-9].
isxdigit
c is a hexadecimal digit [0-9], [A-F] or [a-f].
isalnum c is an alphanumeric (letter or digit).
isline c is a carriage return, new-line, vertical tab, or form-
feed.
isspace c is a space, tab, carriage return, new-line, vertical
tab, or form-feed.
ispunct c is a punctuation character (neither control nor
alphanumeric).
isprint c is a printing character, code 040 (space) through 0176
(tilde).
isgraph c is a printing character, like isprint except false for
space.
iscntrl c is a delete character (0177) or an ordinary control
character (less than 040).
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ctype(3c)
isascii c is an ASCII character, code less than 0200.
DIAGNOSTICS
If the argument to any of these macros is not in the domain of
the function, the result is undefined.
SEE ALSO
stdio(3S), ascii(5).
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