How to measure scanf time in a C program? - c

Question

In the following program, I want to measure the input time i.e. the time taken by user to enter the variables of the array :
#include <stdio.h>
#include <time.h>
int main()
{
int i, array[10];
double user_input_time;
clock_t input_start, input_end;
input_start = clock();
for (i = 0; i < 10; i++)
{
scanf("%d", &array[i]);
}
input_end = clock();
user_input_time = ((double)(input_end - input_start)) / CLOCKS_PER_SEC;
printf("User Input Time : %f\n", user_input_time);
return 0;
}
Above, what I'm getting is the processor time taken not the input time taken by user to enter all the 10 variable of the array.
Please, can someone help me in doing so.

Answer 1

Include: time.h
Use:
int main()
{
time_t start = time(NULL);
//Do your operations here
printf("%.2f\n", (double)(time(NULL) - start));
return 0;
}
Note - We can use clock_gettime for more precise results - link
Using clock_gettime
int main () {
struct timespec start, finish;
clock_gettime(CLOCK_REALTIME, &start);
// do your operations here
clock_gettime(CLOCK_REALTIME, &finish);
long seconds = finish.tv_sec - start.tv_sec;
long ns = finish.tv_nsec - start.tv_nsec;
if (start.tv_nsec > finish.tv_nsec) { // clock underflow
--seconds;
ns += 1000000000;
}
printf("seconds without ns: %ld\n", seconds);
printf("nanoseconds: %ld\n", ns);
printf("total seconds: %e\n", (double)seconds + (double)ns/(double)1000000000);
}

Answer 2

Which precision do you want ?
Because you can use simply time(NULL) if you only want to know the time at the second.
#include <stdio.h>
#include <time.h>
int main(void)
{
int i, array[10];
time_t user_input_time, input_start, input_end;
input_start = time(NULL);
for (i = 0; i < 10; i++)
{
scanf("%d", &array[i]);
}
input_end = time(NULL);
user_input_time = input_end - input_start;
printf("User Input Time : %d second\n", (int)user_input_time);
return 0;
}

Answer 3

You can use gettimeofday() from sys/time.h
#include <stdio.h>
#include <sys/time.h>
int main(void)
{
int i, array[10];
struct timeval input_start, input_end;
gettimeofday(&input_start, NULL);
for (i = 0; i < 10; i++)
{
scanf("%d", &array[i]);
}
gettimeofday(&input_end, NULL);
printf("User Input Time : %d second\n", input_end.tv_sec - input_start.tv_sec);
return 0;
}