PRB: Undefined Pointer Assignment Causes Application Error

• Microsoft FORTRAN PowerStation for Windows 95 and Windows NT, version 4.0

SYMPTOMS

Attempting to assign a pointer result to an undefined pointer causes one of the following application errors at run time:

Under Windows NT version 3.51:

   The instruction at "0x00000000" referenced memory at "0x 00000000".
   The memory could not be "written".

   This program has performed an illegal operation and will be shut down.
   If the problem persists, contact the program vendor.

   Details:

   <program> caused an invalid page fault in module <filename.exe> at
    0137:00401022

CAUSE

The pointer variable is undefined at the time of assignment.

RESOLUTION

The pointer must be defined by either a pointer assignment or an allocate statement.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Sample Code to Illustrate Problem

! Compile options needed: none

      integer, target :: i = 1
      integer, pointer :: p

      p = i        ! undefined pointer

!      p => i      ! definition and assignment
      print *, p
      end