FIX: Negative Value Passed to mktime() Generates Wrong Date

• The Microsoft C/C++ Compiler (CL.EXE) included with: - Microsoft Visual C++, 32-bit Edition, versions 2.0, 2.1

SYMPTOMS

The wrong date is returned when a negative value is passed for the month to the mktime() function.

For example, in the sample code in this article, -1 is passed for the month, so the mktime() function should return December 15, 1994. However, it incorrectly returns January 16, 1995.

RESOLUTION

Verify that the value for the month is greater than or equal to zero, when calling the mktime() function.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Microsoft Visual C++, 32-bit Edition, version 4.0.

MORE INFORMATION

Sample Code to Reproduce Problem

   /* Compile options needed: none
   */

   #include <time.h>
   #include <stdio.h>

   void main() {
       time_t   CurrentTime, NewTime;
       struct tm TimeStruct;

       time ( &CurrentTime );
       TimeStruct = *localtime(&CurrentTime);
       TimeStruct.tm_mday = 15;
       TimeStruct.tm_mon  = -1;
       TimeStruct.tm_year = 95;

       NewTime = mktime (&TimeStruct);
       printf("%s", asctime( &TimeStruct));
   }