FIX: F6099: Integer Overflow with $DEBUG & 32K INTEGER*2 Array

MS-DOS              | OS/2

The information in this article applies to:

• Microsoft FORTRAN for MS-DOS, versions 4.0, 4.01, 4.1, and 5.0
• Microsoft FORTRAN for OS/2, versions 4.1 and 5.0

SYMPTOMS

Programs compiled with FORTRAN versions 4.0, 4.01, 4.1, and 5.0 that have an INTEGER*2 array dimensioned at exactly 32768 and that also access the last element of this array with a variable as a subscript, can give the following error during run time:

   F6099: INTEGER overflow

RESOLUTION

One possible solution is to increase the array size by one.

STATUS

Microsoft has confirmed this to be a problem in FORTRAN versions 4.0, 4.01, 4.1, and 5.0. This problem has been corrected in FORTRAN version 5.1.

MORE INFORMATION

The following code reproduces the problem:

      integer*4 i
      integer*2 n (32768)
      i=32768
      n(i)=1                    ! line 5
      print*,n(32768)
      end

Increasing the dimension of the array by one also removes the integer overflow, as illustrated by the following program:

      integer*4 i
      integer*2 n (32769)
      n(32768)=1
      print*,n(32768)
      end