How do find time at execution of line in C

Asked Jun 25 '19 at 03:23

Active Jun 25 '19 at 03:33

Viewed 33 times

I'm trying to print the time in seconds at when the print is executed.

This is what I have:

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

void printTime(clock_t start){
    clock_t stop = clock();
    double time = (double)(stop-start)/CLOCKS_PER_SEC;
    printf("This is printed at time %f.\n", time);
}

int main(){
    clock_t start = clock();
    sleep(3);
    printTime(start);
    return 0;
}

It would always print the time as 0.000000

asked Jun 25 '19 at 03:23

FiftySentos

If you can use POSIX, `clock_gettime` can be used for this. – Cornstalks Jun 25 '19 at 03:25
`"%e"` is more informative than `"%f"` . – chux - Reinstate Monica Jun 25 '19 at 03:27
@chux: that's highly subjective and not really relevant. – Cornstalks Jun 25 '19 at 03:29
Sorry about the wrong duplicate first :P – Antti Haapala -- Слава Україні Jun 25 '19 at 03:34
It worked with clock_gettime but is there another way to do this? – FiftySentos Jun 25 '19 at 03:39
2

The trouble is that `sleep(3);` doesn't use very much processor time, yet that's what the `clock()` function measures: _The `clock()` function determines the amount of processor time used since the invocation of the calling process, measured in `CLOCKS_PER_SEC`s of a second._ You can use `clock_gettime()` or perhaps `gettimeofday()` to get elapsed time, which is what you want to measure. – Jonathan Leffler Jun 25 '19 at 03:41
@JonathanLeffler the duplicate could use that explanation in one answer :P – Antti Haapala -- Слава Україні Jun 25 '19 at 03:44
Your windows alternative to `clock_gettime` is `QueryPerformanceCounter`. – David C. Rankin Jun 25 '19 at 03:53
@AnttiHaapala: I've added an answer that is fairly comprehensive for the Unix interfaces. – Jonathan Leffler Jun 25 '19 at 07:46

How do find time at execution of line in C

0 Answers0