Problems with unformatted file write/read compatibility between Intel Fortran and gfortran

Question

I am trying to use a code on both Windows with an Intel compiler and on Mac OS with gfortran 6.5.0 and can't get the gfortran version to read parts of an unformatted file written on Windows. I wrote a test code that has the problematic section and verified it works in writing and reading the file on the Intel compiler and on the gfortran compiler. However, if I comment out the write portion and just try to read the file written on the Windows side of the machine (Parallels) with the gfortran version, some of the data is not read properly. I'm including the test code below. The "cel(1), f_ei,f_en,f_egyro,f_wall,f_ex,f_wallBC =" data are not read correctly (the data before that are read in properly, however). Is there some incompatibility in unformatted files?

PROGRAM Testo
  IMPLICIT NONE
  INTEGER, PARAMETER :: ncelMAX=6800
  REAL*8  :: dt
  LOGICAL :: MagON,BFmesh
  INTEGER :: nslice_Ver, nslice_verzr, nslice_Edg, nslice_edgzr
  INTEGER :: nFluid, nChrge, nCel, nBCs, nEdg, nVer , nCelzr, nBCszr, nEdgzr, &
       nVerzr, MinSliceCel, MaxSliceCel, MinSliceCelzr, MaxSliceCelzr
  TYPE cell_obj
     INTEGER*4 verNo(4),edgNo(4)
     INTEGER*4 Bln   !BField Mesh
     REAL*8 f_ei,f_en,f_egyro,f_wall,f_ex, f_wallBC
  END TYPE cell_obj
  TYPE(cell_obj) cel(ncelMAX)
  dt = 2.0E-8
  MagON = .TRUE.
  BFmesh = .TRUE.
  nslice_Ver = 1
  nslice_verzr = 2
  nslice_Edg = 3
  nslice_edgzr = 4
  nFluid = 3
  nChrge = 3
  nCel = 3000
  nBCs = 4000
  nEdg = 5000
  nVer = 6000
  nCelzr = 7000
  nBCszr = 8000
  nEdgzr = 9000
  nVerzr = 10000
  MinSliceCel = 100
  MaxSliceCel = 200
  MinSliceCelzr = 300
  MaxSliceCelzr = 400
  cel(1)%verNo(1) = 1
  cel(1)%verNo(2) = 2
  cel(1)%verNo(3) = 3
  cel(1)%verNo(4) = 4
  cel(1)%edgNo(1) = 1
  cel(1)%edgNo(2) = 2
  cel(1)%edgNo(3) = 3
  cel(1)%edgNo(4) = 4
  cel(1)%Bln = 1000
  cel(1)%f_ei = 2.0E6
  cel(1)%f_en = 2.0E7
  cel(1)%f_egyro = 2.0E8
  cel(1)%f_wall = 3.0E6
  cel(1)%f_ex = 3.0E7
  cel(1)%f_wallBC = 3.0E8
  OPEN(UNIT=10,FILE='restartData_TEST',FORM='UNFORMATTED')
  REWIND(10)
  WRITE(10) dt, MagON, nslice_Ver, nslice_Edg, nslice_verzr, nslice_edgzr, BFmesh
  WRITE(10) nFluid, nChrge, nCel, nBCs, nEdg, nVer , nCelzr, nBCszr, nEdgzr, nVerzr, MinSliceCel, MaxSliceCel,MinSliceCelzr,MaxSliceCelzr
  WRITE(10) cel
  CLOSE(10)
  OPEN(UNIT=10,FILE='restartData_TEST',FORM='UNFORMATTED')
  REWIND(10)
  READ(10) dt,MagON,nslice_Ver,nslice_Edg, nslice_verzr, nslice_edgzr, BFmesh
  PRINT *, "First line = ", dt,MagON,nslice_Ver,nslice_Edg, nslice_verzr, nslice_edgzr, BFmesh
  READ(10) nFluid, nChrge, nCel, nBCs, nEdg, nVer , nCelzr, nBCszr, nEdgzr, nVerzr, MinSliceCel, MaxSliceCel,MinSliceCelzr,MaxSliceCelzr
  PRINT *, "Second line = ", nFluid, nChrge, nCel, nBCs, nEdg, nVer , nCelzr, nBCszr, nEdgzr, nVerzr, MinSliceCel, MaxSliceCel,MinSliceCelzr,MaxSliceCelzr
  READ(10) cel
  PRINT *, "cel(1), verNo(4),edgNo(4) = ",cel(1)%verNo(1),cel(1)%verNo(2),cel(1)%verNo(3),cel(1)%verNo(4),cel(1)%edgNo(1),cel(1)%edgNo(2),cel(1)%edgNo(3),cel(1)%edgNo(4)
  PRINT *, "cel(1), Bln = ",cel(1)%Bln
  PRINT *, "cel(1), f_ei,f_en,f_egyro,f_wall,f_ex,f_wallBC = ",cel(1)%f_ei,cel(1)%f_en,cel(1)%f_egyro,cel(1)%f_wall,cel(1)%f_ex,cel(1)%f_wallBC
  PAUSE 'DONE'
END PROGRAM Testo

score 3 · Answer 1 · answered Apr 13 '20 at 07:14

There is absolutely no guarantee of the portability of Fortran unformatted files - if you don't use exactly the same hardware and compiler combination (down to the version of the compiler) all bets are off. If you need portability use a formatted file, or possibly stream I/O, or probably best one of the portable data formats such as netcdf (https://www.unidata.ucar.edu/software/netcdf/) or hdf5 (https://www.hdfgroup.org/solutions/hdf5/)

Also please don't use the non standard real*8 and integer*4 - see Fortran 90 kind parameter for how to do it properly

Problems with unformatted file write/read compatibility between Intel Fortran and gfortran

1 Answers1