%N isalnumf %F $MIR/src/subs/match.for
%D Return true if char is an alphanumeric character
%P bpw
%: strings
%B
      logical function isalnumf ( char )
      character*1 char

 Isalnumf checks if the character char is an alphanumeric character
 (letter or digit) and returns .true. if so, .false. if otherwise

 Input:
   char:    character to check
