std::chrono::high_resolution_clock::now

 

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std::chrono::high_resolution_clock

Member functions

high_resolution_clock::now

 

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

Returns a time point representing the current point in time.

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>   volatileint sink;// prevents optimization   void do_some_work(std::size_t size){std::vector<int> v(size, 42); sink =std::accumulate(v.begin(), v.end(), 0);// ensures side effect}   int main(){std::cout<<std::fixed<<std::setprecision(9)<<std::left;for(auto size{1ull}; size <1000'000'000ull; size *=100){constauto start = std::chrono::high_resolution_clock::now(); do_some_work(size);constauto end = std::chrono::high_resolution_clock::now();conststd::chrono::duration<double> diff = end - start;std::cout<<"start = "<< start <<"; end = "<< end <<";\n";std::cout<<"diff = "<< diff <<"; size = "<< size <<'\n';}}

Possible output:

start = 2024-10-25 13:37:42.016233947; end = 2024-10-25 13:37:42.016239362; diff = 0.000005415s; size = 1 start = 2024-10-25 13:37:42.016384595; end = 2024-10-25 13:37:42.016386581; diff = 0.000001986s; size = 100 start = 2024-10-25 13:37:42.016394197; end = 2024-10-25 13:37:42.016445830; diff = 0.000051633s; size = 10000 start = 2024-10-25 13:37:42.016452737; end = 2024-10-25 13:37:42.022496657; diff = 0.006043920s; size = 1000000 start = 2024-10-25 13:37:42.022511298; end = 2024-10-25 13:37:42.658639946; diff = 0.636128648s; size = 100000000