isalnum - test for alphanumeric character

Syntax

#include <ctype.h> int isalnum(int c);

Description isalnum() tests whether the character c is a letter or a digit.

	In all cases, the argument c is an int, the value of which must be representable as an unsigned char or must equal the value of the macro EOF. If the argument c has any other value, the behavior is undefined.
Return val.	!= 0 0	Alphanumeric Not alphanumeric
Notes	isalnum() is implemented both as a function and as a macro. To generate a function call, the definition of the macro name must be first undefined (#undef isalnum). The behavior of isalnum() is determined by the classes alpha and digit of the current locale. The current locale is the C locale, unless it was explicitly changed using setlocale().
See also	isalpha(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit(), setlocale(), ctype.h, stdio.h.