FIX: F6100 Reading Maximal Negative Integers

MS-DOS     | WINDOWS NT

The information in this article applies to:

• Microsoft FORTRAN PowerStation for MS-DOS versions 1.0 and 1.0a
• Microsoft FORTRAN PowerStation 32 version 1.0

SYMPTOMS

For any integer data type, reading the smallest negative integer of that range generates the run-time error F6100 indicating that there was an INTEGER overflow on input.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was corrected in Microsoft FORTRAN PowerStation 32, version 4.0.

MORE INFORMATION

The smallest negative integer for each integer data type is:

          -128  Integer*1
        -32768  Integer*2
   -2147483648  Integer*4

Sample Code

C No Compiler options needed

      integer*1 i
      integer*2 j
      integer*4 k
      open(1,file='test.dat')
      do 10 n=3,5
        write(1,*) -2**((2**n-1))
 10   continue

      rewind(1)
      read(1,*,iostat=ierr) i
      if(ierr.eq.6100) then
        print*, 'error reading integer*1 was: ',ierr
      else
        print*, 'integer*1 input: ',i
      end if

      read(1,*,iostat=ierr) j
      if(ierr.eq.6100) then
        print*, 'error reading integer*2 was: ',ierr
      else
        print*, 'integer*2 input: ',j
      end if

      read(1,*,iostat=ierr) k
      if(ierr.eq.6100) then
        print*, 'error reading integer*4 was: ',ierr
      else
        print*, 'integer*4 input: ',k
      end if

      end