diffrence of two time in c++

Question

At first I get a time by

time_t t1 = time(0) 

(is it right for getting current time?) then

time_t t2 = time(0)

now I want the find the difference between t1 and t2 in milliseconds I searched a lot but it didn't worked. lots of casting problems and unable to change it to milliseconds thanks for your help in advance

Solution 1

Use difftime:

double diff = difftime(t2, t1);

This gives you the difference in seconds. Multiply diff by 1000 to get milliseconds.

Solution 2

time() returns an integer type giving the time since the epoch in seconds, therefore you will never get millisecond resolution. Use gettimeofday() instead, that gives a struct with seconds and microseconds:

struct timeval t1, t2;
gettimeofday(&t1, NULL);
/* ... */
gettimeofday(&t2, NULL);
int milliSeconds = (t2.tv_sec - t1.tv_sec) * 1000 + (t2.tv_usec - t1.tv_usec)/1000;

Solution 3

Here is what you need: http://www.cplusplus.com/reference/clibrary/ctime/difftime/