FIX: Incorrect Result Initializing INTEGER*1 Array

Last reviewed: September 11, 1997
Article ID: Q72920
4.00 4.01 4.10 5.00 5.10 | 4.10 5.00 5.10
MS-DOS                   | OS/2
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The information in this article applies to:

  • Microsoft FORTRAN for MS-DOS, versions 4.1, 4.01, 4.1, 5.0, and 5.1
  • Microsoft FORTRAN for OS/2, versions 4.1, 5.0, and 5.1

SYMPTOMS

Programs compiled with Microsoft FORTRAN versions 4.0, 4.01, 4.1, 5.0, and 5.1 that initialize an integer*1 array with negative values (that is, -128 to -1), can give incorrect results when run under MS-DOS or OS/2.

RESOLUTION

Adding an executable statement that uses an element of the array within the DO-LOOP, or disabling loop optimization with /Od, /Odct, or /4Yb when compiling, can prevent the problem from occurring.

STATUS

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

MORE INFORMATION

The following program examples illustrate the problem:

  1. Initializing array using a DO-LOOP.

          integer*1 arr(2)
          do 10 i=1,2
    
            arr(i) = -1
    
10 continue
      write(*,*) arr(1)
      write(*,*) arr(2)
      end

  • Initializing array using a single assignment statement (Microsoft FORTRAN versions 5.0 and 5.1 only).

          integer*1 arr(2)
          arr = -1
          write(*,*) arr(1)
          write(*,*) arr(2)
          end
    

    The programs above produce the following output:

            -1
            -2
    
    
    The following output should be produced:

            -1
            -1
    
    
    To prevent the problem from occurring, add an executable statement that uses an element of the array within the DO-LOOP, or disable loop optimization with /Od, /Odct, or /4Yb when compiling.


  • Additional reference words: 5.00 5.10
    KBCategory: kbtool kbfixlist kbbuglist
    KBSubcategory: FLIss
    Solution Type : kbfix


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    Last reviewed: September 11, 1997
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