Basic Timing: high-resolution clock
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| #include <chrono>
void foo(){
auto start = std::chrono::high_resolution_clock::now();
std::cout<<"Hello World";
auto end = std::chrono::high_resolution_clock::now();
std::chrono::duration<double, std::nano> duration_ns = end - start;
std::chrono::duration<double, std::micro> duration_us = end - start;
std::chrono::duration<double, std::milli> duration_ms(start-end);
std::chrono::duration<double> duration_s(start-end);
std::chrono::duration<double, std::ratio<60>> duration_min = end - start;
std::chrono::duration<double, std::ratio<3600>> duration_hr = end - start;
std::cout << "Took " << duration_s.count() << " ms\n"; // see Hello WorldTook -1.2644e-05 ms
}
|
- Here, we get
duration_X in double. By default, std::chrono::duration<TYPE> returns a long int
- If we accidentally called
start-end, we see negative time value.
- Notice that below seconds, we have
std::nano, etc. Above seconds, we use std::ratio.
Time Conversion To ns, us, s, hour
Use std::duration_cast. It will return a long int.
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| void print_in_different_units( std::chrono::duration<double, std::milli> duration){
long int ns = std::chrono::duration_cast<std::chrono::nanoseconds>(duration).count();
long int us = std::chrono::duration_cast<std::chrono::microseconds>(duration).count();
long int ms = std::chrono::duration_cast<std::chrono::milliseconds>(duration).count();
long int s = std::chrono::duration_cast<std::chrono::seconds>(duration).count();
long int m = std::chrono::duration_cast<std::chrono::minutes>(duration).count();
long int h = std::chrono::duration_cast<std::chrono::hours>(duration).count();
std::cout << "Took " << ns << " ns\n";
}
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