help updating time/timezone

[mac11]

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

#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
 
int main()
{
    char buf[100];
 
    do
    {
    time_t  current_time_t = { 0 }; // time from time()
 
    struct tm *pTimeStruct = 0; 
 
    current_time_t = time(NULL);
    gettimeofday( &tp, 0);
 
    // convert with localtime() and strftime(), then print results for each
    pTimeStruct = localtime(&current_time_t);    
    strftime(buf, sizeof(buf), "%m/%d/%Y  %H:%M:%S", pTimeStruct);
    printf( "%s\n", buf );
 
    } while( !sleep(5) );
 
    return 0;
}

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

[sicarie]

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

#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <unistd.h>
 
int main()
{
    char buf[100];
 
    do
    {
    time_t  current_time_t = { 0 }; // time from time()
 
    struct tm *pTimeStruct = 0; 
 
    current_time_t = time(NULL);
    gettimeofday( &tp, 0);
 
    // convert with localtime() and strftime(), then print results for each
    pTimeStruct = localtime(&current_time_t);    
    strftime(buf, sizeof(buf), "%m/%d/%Y  %H:%M:%S", pTimeStruct);
    printf( "%s\n", buf );
 
    } while( !sleep(5) );
 
    return 0;
}

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

Do you want to change the timezone on the OS, or just have a "different timezone" in your program (which would merely involve a mathematical change of the system time)?

[mac11]

My app needs to update the whole system. I've done more digging and found that I can set an environment variable (TZ) to make everything work as expected.