NAME
isdigit —
decimal-digit character test
SYNOPSIS
#include
<ctype.h>
int
isdigit(int
c);
DESCRIPTION
The
isdigit()
function tests for any decimal-digit character.
RETURN VALUES
The isdigit() function returns zero if the
character tests false or non-zero if the character tests true.
SEE ALSO
isalnum(3), isalpha(3), isascii(3), isblank(3), iscntrl(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), tolower(3), toupper(3), ascii(7)
STANDARDS
The isdigit() function conforms to
ANSI X3.159-1989
(“ANSI C89”).
HISTORY
The isdigit() function first appeared in
Version 7 AT&T UNIX.
CAVEATS
The argument to isdigit() must be
EOF or representable as an unsigned
char; otherwise, the result is undefined.