isdigit
—
decimal-digit character test
Standard C Library (libc, -lc)
#include <ctype.h>
int
isdigit
(int
c);
The isdigit
() function tests for any decimal-digit
character.
The isdigit
() function returns zero if the character
tests false and returns non-zero if the character tests true.
ctype(3),
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)
The isdigit
() function conforms to ANSI
X3.159-1989 (“ANSI C89”).
The argument to isdigit
() must be
EOF
or representable as an unsigned
char; otherwise, the behavior is undefined. See the
CAVEATS section of
ctype(3) for more details.