LinuxQuestions.org - [SOLVED] Gfortran: attribute that requires explicit interface ???

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Gfortran: attribute that requires explicit interface ???

Hi there,

Trying to compile a few Gfortran lines in Ubuntu 12.04 I get this error:

Quote:

lun = newunit(unit)
1
Error: Dummy argument 'unit' of procedure 'newunit' at (1) has an attribute that requires an explicit interface for this procedure

The number one in fact points to the word "unit" not "lun" in the terminal. It got left-shifted when posted.

The code itself:

Code:

program main

  INTEGER*4 counter,lun,unit

  REAL*8, parameter :: pi = 3.141592653589793

  unit = 10

  lun = newunit(unit)

  ...................  

end program main

What does it all mean and how shall I change the code to compile it without an error?

Thanks, - A.

What is the definition of the newunit function? Is it even defined anywhere?

It is not an intrinsic function but is based on an intrinsic function INQUIRE. So, there is a code in the program for that. I copied it from here.

Well, it wanted an interface for this function. In turn an interface needs to be in a module and the module has to be in a separate file too. Otherwise nothing works.

Code:

module sph_persp_mod

  INTERFACE 

    integer function newunit(unit1)

      integer, intent(out), optional :: unit1

    end function newunit

  END INTERFACE

end module

The meaning of all this still eludes me. Whatever works!!!

It's just one of the rules of Fortran syntax ... modules should be in their own files.