std::chrono::high_resolution_clock::now

 

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std::chrono::high_resolution_clock

Member functions

high_resolution_clock::now

 

static std::chrono::time_point<std::chrono::high_resolution_clock> now() noexcept;		(since C++11)

Returns a time point representing the current point in time.

Parameters

(none)

Return value

A time point representing the current time.

Example

Run this code

#include <chrono>
#include <cstddef>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <vector>
 
volatile int sink;
 
void do_some_work(std::size_t size)
{
    std::vector<int> v(size, 42);
    sink = std::accumulate(v.begin(), v.end(), 0); // make sure it is a side effect
}
 
int main()
{
    std::cout << std::fixed << std::setprecision(9) << std::left;
    for (auto size{1ull}; size < 10'00'00'00'00ull; size *= 100)
    {
        const auto start = std::chrono::high_resolution_clock::now();
        do_some_work(size);
        const auto end = std::chrono::high_resolution_clock::now();
 
        const std::chrono::duration<double> diff = end - start;
 
        std::cout << "Time to fill and iterate a vector of " << std::setw(9)
                  << size << " ints : " << diff << '\n';
    }
}

Possible output:

Time to fill and iterate a vector of 1         ints : 0.000006568s
Time to fill and iterate a vector of 100       ints : 0.000002854s
Time to fill and iterate a vector of 10000     ints : 0.000116290s
Time to fill and iterate a vector of 1000000   ints : 0.011742752s
Time to fill and iterate a vector of 100000000 ints : 0.505534949s