static std::chrono::time_point<std::chrono::utc_clock> now(); | (since C++20) |
Returns a time point representing the current point in time. The result is calculated as if by std::chrono::utc_clock::from_sys(std::chrono::system_clock::now()). Implementations may use a more accurate value of UTC time.
(none).
A time point representing the current time.
#include <iostream>
#include <vector>
#include <numeric>
#include <chrono>
volatile int sink;
int main()
{
for (auto size = 1ull; size < 1000000000ull; size *= 100) {
// record start time
auto start = std::chrono::utc_clock::now();
// do some work
std::vector<int> v(size, 42);
sink = std::accumulate(v.begin(), v.end(), 0u); // make sure it's a side effect
// record end time
auto end = std::chrono::utc_clock::now();
std::chrono::duration<double> diff = end-start;
std::cout << "Time to fill and iterate a vector of "
<< size << " ints : " << diff.count() << " s\n";
}
}Possible output:
Time to fill and iterate a vector of 1 ints : 2.43e-07 s Time to fill and iterate a vector of 100 ints : 4.1e-07 s Time to fill and iterate a vector of 10000 ints : 2.519e-05 s Time to fill and iterate a vector of 1000000 ints : 0.00207669 s Time to fill and iterate a vector of 100000000 ints : 0.423087 s
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/chrono/utc_clock/now