isalnum() -- ctype Function (libc)

Check if a character is a number or letter
#include <ctype.h>
int isalnum(c) int c;

isalnum() tests whether the argument  c is alphanumeric (0-9, A-Z, or a-z).
It returns a  number other than zero if c  is of the desired type, and zero
if it is not.  isalnum() assumes that c is an ASCII character or EOF.

Example

For an example of how to use this macro, see the entry for ctype.h.

See Also

ASCII,
libc
ANSI Standard, §7.3.1.1
POSIX Standard, §8.1

© 2012 by Stephen A. Ness