FIX: String Concatenation May Cause Memory Errors (105932)

STATUS

Microsoft has confirmed this to be a problem in FORTRAN PowerStation version 1.0. This problem has been resolved with FORTRAN PowerStation maintenance release version 1.0a for MS-DOS.

FORTRAN PowerStation version 1.0 can be differentiated from the maintenance release version 1.0a by invoking the linker. Typing "link32 | more" from \F32\BIN directory will show version 2.8 for FORTRAN PowerStation version 1.0, and it will show version 1.0f for the maintenance release version 1.0a.

MORE INFORMATION

The following two sample programs demonstrate a memory loss due to string concatenation in the argument list. In both of the following examples, using a temporary variable for the concatenated strings avoids the memory leak.

Sample Code 1

C Compile options needed: none
      character*40 c1,c2
      c1 = 'abcd'
      c2 = 'efgh'
      k = 0
      do i=1,500000
        if(c1//c2 .eq. 'Never') k = k + 1
      end do
      end

The code above will run very slowly, and eventually generate:

run-time error F6700
- heap space limit exceeded

Sample Code 2

C Compile options needed: none
      character fmtout*20,label(1,3)*(9)
      double precision value
      data (label(1,j),j=1,3)/' Label',' Output',' Test'/ 
      data value/3.14159/ 
      fmtout='f10.3'
      write(6,'(3a,''='','//fmtout//')')(label(1,j),j=1,3),value
      end

The above code on execution will generate:

DOSXMSF : error DX2010: invalid pointer passed to free or realloc : 0005F0F8h.
DOSXMSF : error DX2010: invalid pointer passed to free or realloc : 0005F0F8h.
Label Output Test = 3.142

The code does run to completion because this type of DOS-extender error is not fatal.