FIX: "R6001: Null Pointer Assignment" From Loop Optimization

The information in this article applies to:

• Microsoft FORTRAN for MS-DOS and OS/2, version 5.0

SYMPTOMS

An attempt to run an application fails and the following message appears on the screen:

   R6001: null pointer assignment

CAUSE

The application was compiled by FORTRAN version 5.0 with loop optimizations enabled.

RESOLUTION

To work around this problem, perform one of the following steps:

• Specify the /Od or /Odct compiler option switch to disable loop optimization.
• Replace any arrays of CHARACTER*1 variables with character strings.

STATUS

Microsoft has confirmed this to be a problem in FORTRAN version 5.0 for MS-DOS and OS/2. This problem was corrected in FORTRAN version 5.1 for MS-DOS and OS/2.

MORE INFORMATION

The following code example demonstrates this problem.

Sample Code

C Compile options needed: None

      CHARACTER*1 STR1(10), STR2(10)
      DATA STR1 / 'T', '.', 'B', '.', 'C', '.', 4*' ' /
      CALL COPYSTR(STR1, 1, 10, STR2, 1)
      END

      SUBROUTINE COPYSTR(IARRAY, IBEG, IEND, JARRAY, JBEG)
      CHARACTER*1 IARRAY(10), JARRAY(10)

      JPT = JBEG
      DO 100 IGET = IBEG, IEND
        JARRAY(JPT) = IARRAY(IGET)
        JPT = JPT + 1
 100  CONTINUE
      RETURN
      END