Thread: Getting local and greenwich time

Hello,
In the following code, I try to get the local time and greenwich time and find the difference between them. But the output shows both the time values are equal:
diff=0 iTm1=16:34 iTm2=16:34 <-----[gmtime is 13:34 actualy]

When I just retreive gmtime, it works correctly. But when I retreive both local and gmtime, gmtime becomes equal to localtime.

Code:

#include <stdio.h>
#include <time.h>
int main()
{
        time_t iTime;
        struct tm * iTm1;
        struct tm * iTm2;
        int iTimeDifferenceInMinutes;

        time(&iTime);
        iTm1=gmtime(&iTime);
        iTm2=localtime(&iTime);
        iTimeDifferenceInMinutes=(int)((iTm2->tm_hour - iTm1->tm_hour)) * 60;
        printf("diff=%d iTm1=%d:%d iTm2=%d:%d\n", iTimeDifferenceInMinutes,
                        iTm1->tm_hour, iTm1->tm_min,
                        iTm2->tm_hour, iTm2->tm_min);
}

I have a mistake but I couldn't find it...
May someone show me my fault please..?
Thanks.

Originally Posted by Salem

iTm1=gmtime(&iTime);
iTm2=localtime(&iTime);
These return a POINTER to some internal data within the time handing routines.

You need to make a copy of that before calling again.

Eg.
struct tm iTm1 = *gmtime(&iTime);

Thank you.That solved my problem.