C语言编程基础
多线程是程序员必须掌握的一门技术，本文主要是针对于C++新标准中多线程库，需要具备一定C++基础方可学习。
本章节是C++多线程编程第二课，C++不熟悉的可以转接C++专辑教程，本章节主要讲解C++多线程编程中容器创建线程以及数据共享问题。
#include <vector>#include <iostream>#include <thread>void printTest(int num){std::cout << "子线程:" << num << "启动" << std::endl;std::cout << "子线程:" << num << "结束" << std::endl;}int main(){std::vector<std::thread* > test;for (int i = 0; i < 10; i++){test.push_back(new std::thread(printTest, i));}for (auto& pmove : test){pmove->join();}std::cout << "主线程" << std::endl;return 0;}
1.只读数据:稳定安全，不需要特殊处理，直接读即可
#include <vector>#include <iostream>#include <thread>std::vector<int> g_data={ 1,2,3 };void printTest(int num){std::cout << "子线程:" << num << "读操作" << std::endl;for (auto pmove : g_data){std::cout << pmove << std::endl;}}int main(){std::vector<std::thread* > test;for (int i = 0; i < 10; i++){test.push_back(new std::thread(printTest, i));}for (auto& pmove : test){pmove->join();}std::cout << "主线程" << std::endl;return 0;}
2.有读有写：需要做特别处理(写只做写，读只做读操作，保持共享数据只有唯一操作)，不然会引发奔溃
#include <list>#include <iostream>#include <thread>class SeaKing{public:void makeFriend(){for (int i = 0; i < 100000; i++){std::cout << "增加一个" << std::endl;mm.push_back(i);}}void breakUp(){for (int i = 0; i < 100000; i++){if (!mm.empty()){std::cout << "减少一个:"<<mm.front() << std::endl;mm.pop_front();}else{std::cout << "已空" << std::endl;}}}protected:std::list<int> mm;};int main(){SeaKing man;std::thread t1(&SeaKing::makeFriend, &man);std::thread t2(&SeaKing::breakUp, &man);t1.join();t2.join();return 0;}//以上程序会异常退
1.互斥量mutex: 互斥量可以理解为锁，他是一个mutex类的对象
通过调用成员函数lock函数进行加锁
通过调用成员函数unlock函数进行解锁
#include <list>#include <iostream>#include <thread>#include <mutex> //1.包含头文件class SeaKing{public:void makeFriend(){for (int i = 0; i < 100000; i++){m_mutex.lock();std::cout << "增加一个" << std::endl;mm.push_back(i);m_mutex.unlock();}}bool readInfo(){m_mutex.lock(); //2.加锁if (!mm.empty()){std::cout << "减少一个:" << mm.front() << std::endl;mm.pop_front();m_mutex.unlock();return true;}m_mutex.unlock();return false;}void breakUp(){for (int i = 0; i < 100000; i++){int result = readInfo();if (result == false){std::cout << "已空" << std::endl;}}}protected:std::list<int> mm;std::mutex m_mutex; //创建互斥量对象};int main(){SeaKing man;std::thread t1(&SeaKing::makeFriend, &man);std::thread t2(&SeaKing::breakUp, &man);t1.join();t2.join();return 0;}
注意:lock函数与unlock都是成对出现，如果lock了没有调用unlock会引发异常，abort终止程序
2.通过lock_guard加锁。
#include <list>#include <iostream>#include <thread>#include <mutex>class SeaKing{public:void makeFriend(){std::lock_guard<std::mutex> sbguard(m_mutex);for (int i = 0; i < 100000; i++){std::cout << "增加一个" << std::endl;mm.push_back(i);}}bool readInfo(){std::lock_guard<std::mutex> sbguard(m_mutex);if (!mm.empty()){std::cout << "减少一个:" << mm.front() << std::endl;mm.pop_front();return true;}return false;}void breakUp(){for (int i = 0; i < 100000; i++){int result = readInfo();if (result == false){std::cout << "已空" << std::endl;}}}protected:std::list<int> mm;std::mutex m_mutex;};int main(){SeaKing man;std::thread t1(&SeaKing::makeFriend, &man);std::thread t2(&SeaKing::breakUp, &man);t1.join();t2.join();return 0;}
其实lock_guard 在构造函数中进行lock，在析构函数中进行unlock，本质上还是lock与unlock操作。
好了，创建线程就介绍到这里，大家可以先练习一下，下章节讲解共享数据访问。喜欢的不如点个“在看”吧
