c:string:isalnum

isalnum

Syntax:

    #include <cctype>
    int isalnum( int ch );

The function isalnum() returns non-zero if its argument is a numeric digit or a letter of the alphabet. Otherwise, zero is returned.

     char c;
     scanf( "%c", &c );
     if( isalnum(c) )
       printf( "You entered the alphanumeric character %c\n", c );