Test String for alphanumeric characters

Hello Friends, i had used a very useful installscript function for testing a string for alphanumeric characters. The function will accept the string to be tested as a parameter.
You can use the below code and can edit according to your need.

prototype IsAlphanumeric (string);

function IsAlphanumeric (szStuff)
     /* Check if a string is alphanumeric
         In: szStuff -- string to test
         Out: Returns TRUE or FALSE
     */
      #define ALPHANUMERIC_CHARS "abcdefghijklmnopqrstuvwxyz_0123456789"
     // For my purposes, underscore is considered alphanumeric.
     number nPos;
     string szChar;
begin
     for nPos = 0 to StrLength (szStuff)
          StrSub (szChar, szStuff, nPos - 1, 1);
          if !(ALPHANUMERIC_CHARS % szChar) then
              return FALSE;
         endif;
    endfor;
    return TRUE;
end;