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

Description:
    The isalnum function tests if the argument c is an alphanumeric
    character ('a' to 'z', 'A' to 'Z', or '0' to '9').  An alphanumeric
    character is any character for which  isalpha or  isdigit is true.

Returns:
    The isalnum returns zero if the argument is neither an alphabetic
    character nor a digit.  Otherwise, a non-zero value is returned.

See Also:
    isalpha, isdigit, islower

Example:
    #include <stdio.h>
    #include <ctype.h>

    void main()
      {
        if( isalnum( getchar() ) ) {
          printf( "is alpha-numeric\n" );
        }
      }

Classification:
    ANSI

Systems:
    All