Interface Example

The following program includes an explicit interface,

    PROGRAM interface_example
     IMPLICIT NONE
     INTERFACE
      SUBROUTINE expsum(N,K,X,sum)
       INTEGER, INTENT(IN) :: N
       REAL, INTENT(IN)  :: K,X
       REAL, INTENT(OUT)  :: sum
      END SUBROUTINE expsum
     END INTERFACE
     REAL :: sum
      ...
     CALL expsum(10,0.5,0.1,sum)
      ...
    END PROGRAM interface_example

The above interface includes information about the number, type, kind and rank of the dummy arguments of the procedure expsum.

Using an INTERFACE provides for better optimisation and type checking, and allows separate compilation to be performed.