C Illustrates the equivalence of array elements and simple variables

C Created:  Joe Zachary, November 1, 1992
C Modified:


C This subroutine exchanges the values of its two arguments

      SUBROUTINE SWAP (X, Y)

      IMPLICIT NONE
      INTEGER X, Y, Z

      Z = X
      X = Y
      Y = Z

      RETURN
      END


C The main program exercises SWAP

      PROGRAM TESTER

      IMPLICIT NONE
      INTEGER A(5), B, C

      B = 1
      C = 2
      A(2) = 1
      A(3) = 2

      PRINT *, 'Before,    B = ', B, ' and    C = ', C
      CALL SWAP(B, C)
      PRINT *, 'After,     B = ', B, ' and    C = ', C

      PRINT *, 'Before, A(2) = ', A(2), ' and A(3) = ', A(3)
      CALL SWAP(A(2), A(3))
      PRINT *, 'After,  A(2) = ', A(2), ' and A(3) = ', A(3)

      STOP
      END