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Beginner
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Length greater than actual length

Trying to move a legacy code from Visual Studio 2003 and Fortran 9 to Visual Studio 2017 and Fortran 18. Code is a combination of C# and Fortran; some Fortran routines run just fine. Built to .Net 4.5. Compiler options between 9 and 2018 are as close as I can get them. Builds from 2003 only work up to Windows 7, builds from 2017 only run on Windows 10.

While trying to debug an error that causes a crash in the compiled code, ran into this beforehand: "Dummy character variable 'VAR3' has length 1 which is greater than actual variable length 0"

Code is roughly:

subroutine SETOPTIONS(VAR1,VAR2,VAR3,VAR4,VAR5,VAR6,VAR7)
  !DEC$ ATTRIBUTES DLLEXPORT::SETOPTIONS

  implicit none
  INTEGER VAR1
  CHARACTER *1 VAR2,VAR3,VAR5,VAR6
  REAL *4 VAR4
  CHARACTER *40 VAR7
  COMMON /COPTS/ CVAR1,CVAR2,CVAR3,CVAR4
  INTEGER CVAR1
  CHARACTER *1 CVAR2,CVAR3,CVAR5,CVAR6
  REAL *4 CVAR4
  CHARACTER *40 CVAR7

  WRITE(6,*) 'SETOPTIONS'
   CVAR1 = VAR1
   CVAR2 = VAR2
   CVAR3 = VAR3
   CVAR4 = VAR4
   CVAR5 = VAR5
   CVAR6 = VAR6
   CVAR7 = VAR7
end subroutine SETOPTIONS

Both the input variable VAR3 and the output CVAR3 have the same type, and length. Before it executes the line to set CVAR3 = VAR3, watch knows that VAR3 is character with length one and it holds the correct value while CVAR3 is character with length 1 and is empty/space. Changing variable names has no effect. I can hard code CVAR3 to the value and everything else in the subroutine works. There are other variables, such as CVAR2 and VAR2, with the same types and lengths with no issues. Code hasn't changed from the working legacy version to this one.

Ideas? Thanks.

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2 Replies
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Black Belt Retired Employee
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Snippets and paraphrases of code are rarely helpful in diagnosing problems. The error you report is one that Intel Fortran 9 did not check. The compiler now checks the incoming actual argument against the declared length of the dummy. Since you say C# is involved, I'd guess that the C# code is not passing the character lengths at the end of the argument list as Fortran expects. To tell the compiler not to look for the lengths, you would need to add a "!DEC$ ATTRIBUTES REFERENCE :: variablename" for each of the character arguments.

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Beginner
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Thanks!

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