NAME¶

std::chrono::file_clock::now - std::chrono::file_clock::now

Synopsis¶

static std::chrono::time_point<std::chrono::file_clock> now() (since C++20)
noexcept;

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::file_clock::now();
do_some_work(size);
const auto end = std::chrono::file_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