c++ - 错误:尚未声明 'high_resolution_clock'

Question

我在Windows 10上使用g++版本8.1.0，但仍在尝试编译时

auto start=high_resolution_clock::now();
rd(n);
auto stop=high_resolution_clock::now();
auto duration = duration_cast<microseconds>(stop-start);
cout<<duration.count()<<endl;

我得到的错误

error: 'high_resolution_clock' has not been declared
 auto start=high_resolution_clock::now();
            ^~~~~~~~~~~~~~~~~~~~~

我已经包括了chrono和time.h

Answer 1

您需要在std::chrono::，high_resolution_clock和microseconds前面指定duration_cast命名空间限定符，例如:

#include <chrono>

auto start = std::chrono::high_resolution_clock::now();
rd(n);
auto stop = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::microseconds>(stop-start);
std::cout << duration.count() << std::endl;

否则，您可以改用 using语句，例如:

#include <chrono>
using namespace std::chrono;

auto start = high_resolution_clock::now();
rd(n);
auto stop = high_resolution_clock::now();
auto duration = duration_cast<microseconds>(stop-start);
std::cout << duration.count() << std::endl;

要么:

#include <chrono>
using std::chrono::high_resolution_clock;
using std::chrono::microseconds;
using std::chrono::duration_cast;

auto start = high_resolution_clock::now();
rd(n);
auto stop = high_resolution_clock::now();
auto duration = duration_cast<microseconds>(stop-start);
std::cout << duration.count() << std::endl;