BUG: Intrinsic Version of strcmp May Return Incorrect Result

• Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

Explicitly referencing the Null character in the second argument of strcmp causes the intrinsic version of strcmp to incorrectly report the two arguments are not equal. Please see the sample code below.

RESOLUTION

There are two workarounds:

1. Do not explicitly reference the Null character.

2. Do not use the intrinsic version of strcmp.

STATUS

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

MORE INFORMATION

You can enable intrinsic functions either by using of the /Oi compiler switch or #pragma intrinsic. To disable intrinsic functions, remove the /Oi compiler switch, add /Oi-, or use #pragma function to force a function call on a function by function basis. Please see the sample code below for use of the #pragma function.

Sample Code

   /* Build Options: /Oi */
   #include <stdio.h>
   #include <string.h>
   // uncomment the following line for workaround #2
   //#pragma function(strcmp)

   int main(void)
   {
      char somestr [15]  = "Some String";

      somestr[1] = 0;
   // change the following to strcmp(somestr,"S") for workaround #1
      if (strcmp(somestr,"S\0") == 0)
         printf("match: correct\n");
      else
         printf("no match: incorrect\n");
      return 0;
   }

Keywords          : CRTIss vcbuglist500 kbcode kbprg kbbuglist
Version           : 5.0
Platform          : NT WINDOWS
Issue type        : kbbug