在c++ 11中，这是一个非常容易使用的方法。 我们可以从头文件中使用std::chrono::high_resolution_clock 我们可以编写一个方法，以易于阅读的形式打印方法执行时间。

例如，要找到1到1亿之间的所有质数，大约需要1分40秒。 因此，执行时间打印为:

Execution Time: 1 Minutes, 40 Seconds, 715 MicroSeconds, 715000 NanoSeconds

代码在这里:

#include <iostream>
#include <chrono>

using namespace std;
using namespace std::chrono;

typedef high_resolution_clock Clock;
typedef Clock::time_point ClockTime;

void findPrime(long n, string file);
void printExecutionTime(ClockTime start_time, ClockTime end_time);

int main()
{
    long n = long(1E+8);  // N = 100 million

    ClockTime start_time = Clock::now();

    // Write all the prime numbers from 1 to N to the file "prime.txt"
    findPrime(n, "C:\\prime.txt"); 

    ClockTime end_time = Clock::now();

    printExecutionTime(start_time, end_time);
}

void printExecutionTime(ClockTime start_time, ClockTime end_time)
{
    auto execution_time_ns = duration_cast<nanoseconds>(end_time - start_time).count();
    auto execution_time_ms = duration_cast<microseconds>(end_time - start_time).count();
    auto execution_time_sec = duration_cast<seconds>(end_time - start_time).count();
    auto execution_time_min = duration_cast<minutes>(end_time - start_time).count();
    auto execution_time_hour = duration_cast<hours>(end_time - start_time).count();

    cout << "\nExecution Time: ";
    if(execution_time_hour > 0)
    cout << "" << execution_time_hour << " Hours, ";
    if(execution_time_min > 0)
    cout << "" << execution_time_min % 60 << " Minutes, ";
    if(execution_time_sec > 0)
    cout << "" << execution_time_sec % 60 << " Seconds, ";
    if(execution_time_ms > 0)
    cout << "" << execution_time_ms % long(1E+3) << " MicroSeconds, ";
    if(execution_time_ns > 0)
    cout << "" << execution_time_ns % long(1E+6) << " NanoSeconds, ";
}

我建议使用steady_clock，它保证是单调的，不像high_resolution_clock。

#include <iostream>
#include <chrono>

using namespace std;

unsigned int stopwatch()
{
    static auto start_time = chrono::steady_clock::now();

    auto end_time = chrono::steady_clock::now();
    auto delta    = chrono::duration_cast<chrono::microseconds>(end_time - start_time);

    start_time = end_time;

    return delta.count();
}

int main() {
  stopwatch(); //Start stopwatch
  std::cout << "Hello World!\n";
  cout << stopwatch() << endl; //Time to execute last line
  for (int i=0; i<1000000; i++)
      string s = "ASDFAD";
  cout << stopwatch() << endl; //Time to execute for loop
}

输出:

Hello World!
62
163514

这是一个非常基本的定时器类，你可以根据自己的需要进行扩展。我想要一些直接的东西，可以在代码中干净地使用。你可以通过这个链接来修改代码:http://tpcg.io/nd47hFqr。

class local_timer {
    private:
        std::chrono::_V2::system_clock::time_point start_time;
        std::chrono::_V2::system_clock::time_point stop_time;
        std::chrono::_V2::system_clock::time_point stop_time_temp;
        std::chrono::microseconds most_recent_duration_usec_chrono;
        double most_recent_duration_sec;
    public:

        local_timer() {

        };

        ~local_timer() {

        };

        void start() {
            this->start_time = std::chrono::high_resolution_clock::now();
        };

        void stop() {
            this->stop_time = std::chrono::high_resolution_clock::now();
        };

        double get_time_now() {
            this->stop_time_temp = std::chrono::high_resolution_clock::now();
            this->most_recent_duration_usec_chrono = std::chrono::duration_cast<std::chrono::microseconds>(stop_time_temp-start_time);
            this->most_recent_duration_sec = (long double)most_recent_duration_usec_chrono.count()/1000000;
            return this->most_recent_duration_sec;
        };

        double get_duration() {
            this->most_recent_duration_usec_chrono = std::chrono::duration_cast<std::chrono::microseconds>(stop_time-start_time);
            this->most_recent_duration_sec = (long double)most_recent_duration_usec_chrono.count()/1000000;
            return this->most_recent_duration_sec;
        };


};

这个存在的用处

#include <iostream>
#include "timer.hpp" //if kept in an hpp file in the same folder, can also before your main function

int main() {
    //create two timers
    local_timer timer1 = local_timer();
    local_timer timer2 = local_timer();
    
    //set start time for timer1
    timer1.start();
    //wait 1 second
    while(timer1.get_time_now() < 1.0) {
    }
    //save time
    timer1.stop();
    //print time
    std::cout << timer1.get_duration() << " seconds, timer 1\n" << std::endl;

    timer2.start();
    for(long int i = 0; i < 100000000; i++) {
        //do something
        if(i%1000000 == 0) { 
            //return time since loop started
            std::cout << timer2.get_time_now() << " seconds, timer 2\n"<< std::endl;
        }
        
    }
    return 0;
}

因为没有一个提供的答案是非常准确的或可复制的结果，我决定添加一个链接到我的代码，具有亚纳秒的精度和科学统计。

Note that this will only work to measure code that takes a (very) short time to run (aka, a few clock cycles to a few thousand): if they run so long that they are likely to be interrupted by some -heh- interrupt, then it is clearly not possible to give a reproducable and accurate result; the consequence of which is that the measurement never finishes: namely, it continues to measure until it is statistically 99.9% sure it has the right answer which never happens on a machine that has other processes running when the code takes too long.

https://github.com/CarloWood/cwds/blob/master/benchmark.h#L40

对于旧的c++或C来说很简单:

#include <time.h> // includes clock_t and CLOCKS_PER_SEC

int main() {

    clock_t start, end;

    start = clock();
    // ...code to measure...
    end = clock();

    double duration_sec = double(end-start)/CLOCKS_PER_SEC;
    return 0;
}

计时精度(秒)为1.0/CLOCKS_PER_SEC

在c++ 11中，这是一个非常容易使用的方法。 我们可以从头文件中使用std::chrono::high_resolution_clock 我们可以编写一个方法，以易于阅读的形式打印方法执行时间。

例如，要找到1到1亿之间的所有质数，大约需要1分40秒。 因此，执行时间打印为:

Execution Time: 1 Minutes, 40 Seconds, 715 MicroSeconds, 715000 NanoSeconds

代码在这里:

#include <iostream>
#include <chrono>

using namespace std;
using namespace std::chrono;

typedef high_resolution_clock Clock;
typedef Clock::time_point ClockTime;

void findPrime(long n, string file);
void printExecutionTime(ClockTime start_time, ClockTime end_time);

int main()
{
    long n = long(1E+8);  // N = 100 million

    ClockTime start_time = Clock::now();

    // Write all the prime numbers from 1 to N to the file "prime.txt"
    findPrime(n, "C:\\prime.txt"); 

    ClockTime end_time = Clock::now();

    printExecutionTime(start_time, end_time);
}

void printExecutionTime(ClockTime start_time, ClockTime end_time)
{
    auto execution_time_ns = duration_cast<nanoseconds>(end_time - start_time).count();
    auto execution_time_ms = duration_cast<microseconds>(end_time - start_time).count();
    auto execution_time_sec = duration_cast<seconds>(end_time - start_time).count();
    auto execution_time_min = duration_cast<minutes>(end_time - start_time).count();
    auto execution_time_hour = duration_cast<hours>(end_time - start_time).count();

    cout << "\nExecution Time: ";
    if(execution_time_hour > 0)
    cout << "" << execution_time_hour << " Hours, ";
    if(execution_time_min > 0)
    cout << "" << execution_time_min % 60 << " Minutes, ";
    if(execution_time_sec > 0)
    cout << "" << execution_time_sec % 60 << " Seconds, ";
    if(execution_time_ms > 0)
    cout << "" << execution_time_ms % long(1E+3) << " MicroSeconds, ";
    if(execution_time_ns > 0)
    cout << "" << execution_time_ns % long(1E+6) << " NanoSeconds, ";
}