C++ Thread constructor用法及代码示例

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− 函数指针、成员指针或任何类型的 move-constructible 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

空

异常

空

数据竞争

修改 x。

示例

在下面的例子中解释了 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面的程序，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