C Illustrates how DO loops work

      PROGRAM LOOPER
      IMPLICIT NONE
      INTEGER I, FIRST, LAST, STEP

      PRINT *, 'Please enter FIRST: '
      READ *, FIRST

      PRINT *, 'Please enter LAST: '
      READ *, LAST

      PRINT *, 'Please enter STEP: '
      READ *, STEP

      DO I = FIRST, LAST, STEP
        PRINT *, 'In the loop!  The value of I is ', I
      ENDDO

      PRINT *, 'The loop has ended!  The value of I is ', I

      STOP
      END