Question

I have an old Fortran program for reading records from text files. The records are of the form:

record_type field1 field2 ... fieldN ;

These records might spread over several lines, the character ; shows that the record has finished. The old code is:

2 read(data,"(a130)",end=3)line
  shift=adrec(nbrec)-1
  read(line,*,end=1)typrec(nbrec),(field(shift+i),i=1,65)
1 do
    do j=shift+1,shift+i-1
      k=index(field(j),';')
      if(k .ne. 0)then
        if(k .eq. 1)then
          adrec(nbrec+1)=j
        else
          field(j)(k:)=''
          adrec(nbrec+1)=j+1
        endif
          go to 2
      endif
    endo
    read(data,"(a130)")line
    read(line,*,end=1)(field(shift+i),i=1,65)
  enddo
3 continue

This code works with Intel Compiler (ifort) as it is. With gfortran it fails! The first problem is that the implicit read on the third line, with ifort, gives i to be equal to the number of fields actually read, while in gfortran it always gives 65. The second problem is that in the same implicit read, with ifort, the character ; is read as a normal field but with gfortran is skipped.

Anyone can help me solve these two problems? Any other ideas for replacing the code all together are also welcome.

Answer 1

Does this work? Aside from do while (and exit control structures…), this is f77 compliant (I think). The do whiles could relatively easily be replaced by goto/continue if necessary. I don’t know what type you ultimately want the strings to be, so I return strings (and assume a field can’t be longer than 24 characters)…I also assume a “line” can’t be longer than 1024 characters.
Sorry about the lack of comments, but the function names are descriptive enough I think. Generally, I think it is a good idea to use functions/subroutines when programming as that makes the code much more readible…

  program main
  character*1024 line
  integer stat,stat2,i,nf
  character*24 fld
  character*16 fmt

  open(unit=21,file='test.dat',status='old')
  stat=0
  do while(stat.eq.0)
     call readline(21,line,stat)
     stat2=0
     i=1
     do while(.true.)
        call getfield(line,fld,stat2)
        if(stat2.ne.0) exit
        i=i+1
        write(*,*) i,stat2,fld
     enddo
     write(*,*) " "
  enddo


  end

  subroutine getfield(line,field,stat)
  integer l,i,stat
  character*(*) line,field
  !Get first field and shift the line
  l=1
  if(line.eq.' ')then
     stat=1
  else
     stat=0
  endif
  do while (line(l:l).eq.' ')
     l=l+1
  enddo
  i=l
  do while (line(i:i).ne.' ')
     i=i+1
  enddo

  if((line(l:l).eq.'"').or.(line(l:l).eq."'"))then
     do while(line(i:i).ne.line(l:l))
        i=i+1
     enddo
  endif

  field=line(l:i)
  line=line(i+1:)
  return
  end

  subroutine readline(unit,line,stat)
  integer unit
  character*(*) line
  integer stat,i
  !read one "line"  Lines are sequences seperated by ';' (can have newlines in there) 

  stat=0
  i=1
  do while (.true.)
     read(unit,'(A)',end=100) line(i:)
     i=index(line,';')
     if(i.eq.0)then
        i=len_trim(line)+2
     else
        line(i:)=' ' !remove the trailing semicolon.
        exit
     endif
  enddo

  return
 100  continue
  stat=1
  return
  end