C++代码块执行时间

以下是两种C++计算代码块执行时间的方法：

1.使用clock()函数计算代码块执行时间

#include <iostream>
#include <ctime>

using namespace std;

int main() {
    clock_t start, finish;
    double time_length;

    start = clock(); // 记录开始时间

    // 代码块
    for (int i = 0; i < 100000000; i++) {
        // Do something
    }

    finish = clock(); // 记录结束时间

    time_length = (double)(finish - start) / CLOCKS_PER_SEC; // 计算代码块执行时间

    cout << "Time used is " << time_length << " second." << endl;

    return 0;
}

2.使用自定义计时器类计算代码块执行时间

#include <iostream>
#include <chrono>

using namespace std;

class Timer {
public:
    Timer() {
        m_StartTimepoint = chrono::high_resolution_clock::now();
    }

    ~Timer() {
        Stop();
    }

    void Stop() {
        auto endTimepoint = chrono::high_resolution_clock::now();

        auto start = chrono::time_point_cast<chrono::microseconds>(m_StartTimepoint).time_since_epoch().count();
        auto end = chrono::time_point_cast<chrono::microseconds>(endTimepoint).time_since_epoch().count();

        auto duration = end - start;
        double ms = duration * 0.001;

        cout << "Time used is " << ms << " ms." << endl;
    }

private:
    chrono::time_point<chrono::high_resolution_clock> m_StartTimepoint;
};

int main() {
    {
        Timer timer;

        // 代码块
        for (int i = 0; i < 100000000; i++) {
            // Do something
        }
    }

    return 0;
}