C++ 线程库 - 函数构造函数

描述

它用于构造线程对象。

声明

以下是 std::thread::thread 函数的声明。

thread() noexcept;
template <class Fn, class... Args>
explicit thread (Fn&& fn, Args&&... args);
thread (const thread&) = delete;	
thread (thread&& x) noexcept;

C++11

thread() noexcept;
template <class Fn, class... Args>
explicit thread (Fn&& fn, Args&&... args);
thread (const thread&) = delete;	
thread (thread&& x) noexcept;

参数

• fn − 它是一个指向函数的指针，指向成员的指针，或任何可移动构造的函数对象。

• args... − 传递给 fn 调用的参数。

• x − 它是一个线程对象。

返回值

无

异常

无

数据竞争

修改 x。

示例

下面的示例解释了 std::thread::thread 函数。

#include <iostream>
#include <utility>
#include <thread>
#include <chrono>
#include <functional>
#include <atomic>
 
void f1(int n) {
   for (int i = 0; i < 5; ++i) {
      std::cout << "1st Thread executing\n";
      ++n;
      std::this_thread::sleep_for(std::chrono::milliseconds(10));
   }
}

void f2(int& n) {
   for (int i = 0; i < 5; ++i) {
      std::cout << "2nd Thread executing\n";
      ++n;
      std::this_thread::sleep_for(std::chrono::milliseconds(10));
   }
}
 
int main() {
   int n = 0;
   std::thread t1;
   std::thread t2(f1, n + 1);
   std::thread t3(f2, std::ref(n));
   std::thread t4(std::move(t3));
   t2.join();
   t4.join();
   std::cout << "Final value of n is " << n << '\n';
}

让我们编译并运行上述程序，这将产生以下结果：

1st Thread executing
2nd Thread executing
1st Thread executing
2nd Thread executing
1st Thread executing
2nd Thread executing
1st Thread executing
2nd Thread executing
2nd Thread executing
1st Thread executing
Final value of n is 5