c++双线程进入死循环的问题

Question

想写一个猜数字游戏，一个线程游戏，一个线程计时，我想把线程封装到一个类里，然后一运行，设置完时间，程序就死循环了

下面是我的代码 不知道咋改了

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <windows.h>
using namespace std;
clock_t begin, end;
double usetime;
int n,num
DWORD WINAPI monitor(LPVOID lpParameter) {
    end = clock();
    usetime = double(end - begin) / CLOCKS_PER_SEC;
}
DWORD WINAPI game(LPVOID lpParameter) {
    cout << "请输入一个数：";
    cin >> n;
    if (n > num) {cout << "太大了" << endl;} 
    else if (n < num) {cout << "太小了" << endl;}
}
class Thread {
    public:
        HANDLE h1, h2;
        void Create() {
            h2 = CreateThread(NULL, 0, game, NULL, 0, NULL);
            h1 = CreateThread(NULL, 0, monitor, NULL, 0, NULL);
        }
};
class Game : public Thread {
    public:
        int sec, flag=0;
        void Play() {
            srand(time(NULL));
            int num = rand() % 10000 + 1;
            cout << "请设置游戏时间（秒）：";
            cin >> sec;
            begin = clock();
            while (n != num) {
                Create();
                if (usetime > sec) {
                    flag = 1;
                    break;
                }
            }
            if (flag) {cout << "游戏超时，该数字为" << num << endl;} 
            else {cout << "正确猜出数" << num << endl;}
        }
};
int main() {
    Game game;
    game.Play();
    system("pause");
    return 0;
}

Answer 1

你的代码错误挺多的，num应该用全局变量，在play函数中，不应该重新声明新的int num了。线程应该用循环执行，否则没有任何意义。你的代码修改了一下，代码修改后的运行结果：

代码修改如下：

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <windows.h>
using namespace std;

clock_t begintime, endtime;
double usetime;
int n, num;
int g_flag = 1;
int sec;
DWORD WINAPI monitor(LPVOID lpParameter) {
    
    while (g_flag)
    {
        endtime = clock();
        Sleep(10); //10ms判断一次
    }
    return 0;
}
DWORD WINAPI game(LPVOID lpParameter) {
    while (g_flag)
    {
        cout << "请输入一个数：";
        cin >> n;
        if (n > num) { cout << "太大了" << endl; }
        else if (n < num) { cout << "太小了" << endl; }
        else {
            //cout << "猜对了" << endl; 
            g_flag = 0;
        }
    }
    
    return 0;
}
class Thread {
public:
    HANDLE h1, h2;
    void Create() {
        h2 = CreateThread(NULL, 0, game, NULL, 0, NULL);
        h1 = CreateThread(NULL, 0, monitor, NULL, 0, NULL);
    }
};
class Game :public Thread{
public:
    void Play() {
        srand(time(NULL));
        num = rand() % 10000 + 1;
        cout << "请设置游戏时间（秒）：";
        cin >> sec;
        
        usetime = 0; //初始化时间
        begintime = clock(); //初始化时间

        Create();
        while (usetime < sec && g_flag)
        {
            usetime = double(endtime - begintime) / CLOCKS_PER_SEC;
        }

        if(g_flag == 0) { cout << "正确猜出数" << num << endl; }
        else { 
            g_flag = 0; //这里让线程结束
            cout << "游戏超时，该数字为" << num << endl;
        }
    }
};
int main() {
    Game game;
    game.Play();
    system("pause");
    return 0;
}