function Reverse( byref source as string ) as string
     dim as integer first => 0
     dim as integer last => Len(source)-1
      
     while( first < last )
         Swap source[first], source[last]
         first += 1 : last -= 1
     wend
     return source
end function

sub ReverseCopy( byref source as string, byref dest as string )
     dest = source
     dest = Reverse( dest )
end sub

     '' ----------------------------------------------------
     dim as string s
     ReverseCopy( "0123456789", s )
     print s ; " -> " ; Reverse( s )
      
     sleep : end 0