Question

Possible Duplicate:
The C clock() function just returns a zero

I ran the following code to test the working of clock() function. I work on ubuntu 12.04.

#include <stdio.h>
#include <time.h>
#include <iostream>
using namespace std;


double diffclock(clock_t clock1,clock_t clock2)
{
double diffticks=clock1-clock2;
double diffms=(diffticks*10)/CLOCKS_PER_SEC;
return diffms;
}

int main()
{
string name;
int i;
clock_t begin=clock();
cout << "Hi what is your name? ";
getline(cin, name);
clock_t end=clock();
cout << "Time elapsed: " << double(diffclock(end,begin)) << " ms"<< endl;
return 0;
}

But no matter how much time i take to write my name, the time elapsed is always shown as 0ms.

Can you tell me what is the problem?

Answer 1

clock() returns the number of ticks USED SINCE THE PROGRAM STARTED executing. There is no need (in this specific) example to get the clock_t begin value.

Try printing out both the begin and end values and see what they are. They’re likely both 0 or close to 0 as waiting for user input doesn’t use CPU time.

Either way, I recommend the time() function as you don’t need tick precision.
http://www.cplusplus.com/reference/clibrary/ctime/time/