C ++如何测量和比较两个函数之间的执行时间

Question

I'm new to C++

And I'm trying to build a simple project, so I need to measure and compare execution time between two functions, to see which one is better for performance time,

I know there are a lot of ways like calculating start and end time and calc difference But that's not usually true, so there's no right way to do it?

my old code:

#include <chrono>

auto begin = std::chrono::steady_clock::now();
/* some code*/
auto end = std::chrono::steady_clock::now();

auto time = (end - begin).count();

Any help please?

Answer 1

using C++ Timeit library :

Compare Time Between Two Functions

void func1() { /* some code */ }
void func2() { /* some code */ }

compareit(1000,func1,func2);

result

[COMPARE IT] first(675)  > second(22) x30

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NOTES

first means first function func1()

second means second function func2()

x30 means the func2() faster than func1() by 30 times

675 22 it is a elapsed time to execute func1 , func2 for 1000 times

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Measure Time For One Function

void func() { for (auto i = 0; i < 10; i++) sqrt(i); }
std::cout << timeit(1000, func).nanoseconds() << std::endl;

result

225451