◄Up► ◄Contents► ◄Index► ◄Back►
─────CALL───────────────────────────────────────────────────────────────────
 
     Action
 
     Invokes a subroutine.
 
     Syntax
 
     CALL sub [([actuals])]
 
     Parameter          Description
 
     sub                The name of the subroutine to execute.
 
     actuals            One or more actual arguments.
 
                        If there is more than one argument, they are
                        separated by commas.
 
     Remarks
 
     A subroutine can be called from any program unit.
 
     A CALL statement must contain as many actual arguments as there
     are formal arguments in the corresponding SUBROUTINE statement
     (unless the C and VARYING attributes were used in declaring the
     subroutine), and the corresponding arguments must have the same
     type.
 
     FORTRAN does not support recursive subroutine calls.
 
     An alternate-return feature lets you specify the statement to
     which a subroutine should return control.
 
        1. Choose the statements in the calling routine to which you
           wish to return control. Precede these labels with asterisks
           when calling the subroutine:
 
               CALL INVERT (row, column, *100, *200, *500)
 
        2. In the corresponding SUBROUTINE, enter asterisks for the
           formal arguments corresponding to the label arguments in the
           CALL statement:
 
               SUBROUTINE INVERT (r, c, *, *, *)
 
        3. In the subroutine, have at least one RETURN statement for
           each alternate return. As arguments for these RETURN
           statements, specify a 1 for the RETURN statement to return
           control to the first statement label; a 2 for the RETURN
           statement for the second label, and so on.
 
     Examples
           .
           .
           .
           IF (ierr .NE. 0)  CALL Error (ierr)
           END
     C
           SUBROUTINE Error (ierrno)
           WRITE (*, 200) ierrno
       200 FORMAT (1X, 'error', I5, ' detected')
           END
 
     C     This example illustrates the alternate return feature:
         1 CALL Boomerang (count, *10, j, *20, *30)
           WRITE (*, *) 'normal return'
           GOTO 40
        10 WRITE (*, *) 'returned to 10'
           GOTO 40
        20 WRITE (*, *) 'returned to 20'
           GOTO 40
        30 WRITE (*, *) 'returned to 30'
        40 CONTINUE
           .
           .
           .
           SUBROUTINE Boomerang (i, *, j, *, *)
           IF (i .EQ. 10)  RETURN 1
           IF (i .EQ. 20)  RETURN 2
           IF (i .EQ. 30)  RETURN 3
           RETURN
                                    -♦-