help updating time/timezone

I have a question about getting the current time. Here is a small program that just gets the time and displays it:

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1. #include <stdio.h>
2. #include <time.h>
3. #include <sys/time.h>
4. #include <unistd.h>
5.  
6. int main()
7. {
8.     char buf[100];
9.  
10.     do
11.     {
12.     time_t  current_time_t = { 0 }; // time from time()
13.  
14.     struct tm *pTimeStruct = 0; 
15.  
16.     current_time_t = time(NULL);
17.     gettimeofday( &tp, 0);
18.  
19.     // convert with localtime() and strftime(), then print results for each
20.     pTimeStruct = localtime(&current_time_t);    
21.     strftime(buf, sizeof(buf), "%m/%d/%Y  %H:%M:%S", pTimeStruct);
22.     printf( "%s\n", buf );
23.  
24.     } while( !sleep(5) );
25.  
26.     return 0;
27. }

The issue I'm having is that if I start this program and then change the timezone the time being displayed does not reflect the time shift, but if I kill the program and start it again the time will reflect the new timezone.

Is there something that I should do to make the time() call reflect the timezone update? I'm not sure if this is a c++ issue or maybe an OS issue. I'm using Linux if that makes any difference.

Thanks in advance