<分区>
我正在尝试实现一个通用函数,该函数记录另一个函数运行的时间。
#include <iostream>
#include <future>
#include <thread>
#include <vector>
#include <functional>
#include <numeric>
#include <memory>
template<typename Res, typename Func, typename...Args>
std::pair<Res, double> ftime(Func fun, Args&&... args)
{
auto start = std::chrono::system_clock::now();
Res res = fun(std::forward<Args>(args)...);
std::chrono::duration<double> duration = std::chrono::system_clock::now() - start;
return std::make_pair(res, duration.count());
}
int main ()
{
std::vector<int> values (100, 1);
auto res = ftime(std::accumulate, values.begin(), values.end(), 0);
std::cout << "Sum up " << values.size() << std::endl;
std::cout << "Serial sum = " << res.first << " took : " << res.second << std::endl;
}
以上代码编译失败,出现以下错误:
sum_1000000.cpp: In function ‘int main()’:
sum_1000000.cpp:22:68: error: no matching function for call to ‘ftime(<unresolved overloaded function type>, std::vector<int>::iterator, std::vector<int>::iterator, int)’
auto res = ftime(std::accumulate, values.begin(), values.end(), 0);
^
sum_1000000.cpp:10:24: note: candidate: template<class Res, class Func, class ... Args> std::pair<Res, double> ftime(Func, Args&& ...)
std::pair<Res, double> ftime(Func fun, Args&&... args)
^
sum_1000000.cpp:10:24: note: template argument deduction/substitution failed:
sum_1000000.cpp:22:68: note: couldn't deduce template parameter ‘Res’
auto res = ftime(std::accumulate, values.begin(), values.end(), 0);
据我所知,编译器无法识别 std::acumulate 函数的模板类型。我做错了什么?
谢谢