[C++知识库]C++多线程顺序打印

#include <bits/stdc++.h>
#include <thread>
#include <mutex>

using namespace std;

mutex g_mu;
condition_variable cond;
int g_val;
const int N = 4; //指定打印的字母个数，A为1，AB为2，ABC为3
const int MAXTIME = 100; //打印次数

class printC
{
public:
    printC(char _c, int _ct = 0) : c(_c), cur_time(_ct)
    {
    }
    void operator()() //重载()，使得对象变成仿函数
    {
        while (true)
        {
            if (cur_time < MAXTIME)
            {
                unique_lock<mutex> guard(g_mu); //加锁，进入临界区
                cond.wait(guard, [this]         //引用this指针
                          {
                    if(this->c -'A' == g_val && 
                    this->cur_time < MAXTIME)
                        return true;
                    else
                        return false; });                 //等待条件满足
                cout << c;
                g_val = (g_val + 1) % N;
                ++cur_time;
                // guard.unlock();
                cond.notify_all();
            }
            else
            {
                return;
            }
        }
    }

private:
    char c;
    int cur_time = 0;
};

void test()
{
    vector<thread> ts;
    for (int i = 0; i < N; ++i)
    {
        printC tmp(i + 'A');
        ts.push_back(move(thread(move(tmp)))); //move函数进行资源转移，提高效率
    }
    for (int i = 0; i < N; ++i)
    {
        ts[i].join();
    }
}

int main()
{

    test();
    return 0;
}

注意bits/stdc++.h头文件只能在g++编译器下使用，Windows自带的编译器需要手动添加这个头文件。或者将#include<bits/stdc++.h>替换成下面的头文件引入：

#include<iostream>
#include<vector>