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错误:未声明“high_resolution_clock”

high-resolution-clock chrono time c++

0

theebugger · 技术社区 · 5 年前

我在windows 10上使用g++8.1.0版本,但当我尝试编译时

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;

我得到的错误是

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

我把chrono和time都包括在内了。h

2 回复 | 直到 5 年前

1

2

Remy Lebeau 5 年前

您需要指定 std::chrono:: 前面的名称空间限定符 high_resolution_clock , microseconds ,以及 duration_cast 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,您可以使用 using 取而代之的是陈述,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;

或者:

#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;

2

0

theebugger 5 年前

哦,我刚找到解决办法, 我忘了使用chrono命名空间所以代码应该是:

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