CLOCKS_PER_SEC Not Matching Results From std::clock()

问题

I'm using the following short program to test std::clock():

#include <ctime>
#include <iostream>

int main()
{   
    std::clock_t Begin = std::clock();

    int Dummy;
    std::cin >> Dummy;

    std::clock_t End = std::clock();

    std::cout << "CLOCKS_PER_SEC: " << CLOCKS_PER_SEC << "\n";
    std::cout << "Begin: " << Begin << "\n";
    std::cout << "End: " << End << "\n";
    std::cout << "Difference: " << (End - Begin) << std::endl;
}

However, after waiting several seconds to input the "dummy" value, I get the following output:

CLOCKS_PER_SEC: 1000000
Begin: 13504
End: 13604
Difference: 100

This obviously doesn't make much sense. No matter how long I wait, the difference is always somewhere around 100.

What am I missing? Is there some header I forgot to include?

I'm using Xcode with GCC 4.2.

回答1:

clock() counts CPU time, so it's not adding any time if it's sitting around waiting for input.

来源：https://stackoverflow.com/questions/6114392/clocks-per-sec-not-matching-results-from-stdclock