// Title  : COMAL Example 15
// Author : John Walsh
// Date   : 16 April 2000
//
first_actual$ := "First"
second_actual$ := "Second"
//
PRINT "Values at start of program are :"
PRINT "first_actual$  = "; first_actual$
PRINT "second_actual$  = "; second_actual$
//
exchange (first_actual$, second_actual$)
//
PRINT "Values at end of program are :"
PRINT "first_actual$  = "; first_actual$
PRINT "second_actual$  = "; second_actual$
END
//
PROC exchange (REF formal_one$, REF formal_two$)
    LOCAL swap$
    swap$ := formal_one$
    formal_one$ := formal_two$
    formal_two$ := swap$
ENDPROC exchange