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