Microsoft KB Archive/105932

= FIX: String Concatenation May Cause Memory Errors =

Article ID: 105932

Article Last Modified on 10/2/2003

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APPLIES TO


 * Microsoft FORTRAN PowerStation 1.0 Standard Edition
 * Microsoft Fortran PowerStation 1.0a for MS-DOS

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This article was previously published under Q105932



SYMPTOMS
Character string concatenations that involve the automatic creation of temporary variables may cause the following memory related run-time problems:


 * Very slow execution of the application
 * F6700
 * DX2010



RESOLUTION
This memory loss can be avoided by assigning the concatenated strings to a temporary character string variable.



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.

Additional query words: 1.00 buglist1.00 fixlist1.00a

Keywords: kbbug kbfix KB105932

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