前置++和后置++的区别

今天看了一下windows c中多线程编程，写了一小段程序。死活跑出结果，先贴一下我的代码

#include <windows.h>
#include <iostream.h>
#include <string>

using namespace std;

DWORD WINAPI countThread1(LPVOID argv);//声明一个线程函数
DWORD WINAPI countThread2(LPVOID argv);

int main(){
    //创建两个线程
    HANDLE handle1 = CreateThread(NULL, 0, countThread1, NULL, 0, NULL);

    WaitForSingleObject(handle1, INFINITE);


    return 0;
}
//下面是两个线程函数
DWORD WINAPI countThread1(LPVOID argv){
    int i = 0;
    cout<<"i am in"<<endl;
    while(i++){　　　　　　//这里开始没看出来有错，开始没注意这段代码，以为是main里面出错了。后面输出i am in我知道这段代码有问题了
        if(10 == i)
            ExitThread(0);
        cout<<"this is thread2 and i = "<<i<<endl;
        Sleep(1000);
    }

    return 0;
}
DWORD WINAPI countThread2(LPVOID argv){
    int i = 0;
    while(i++){
        if(10 == i)
            ExitThread(0);
        cout<<"this is thread2 and i = "<<i<<endl;
        Sleep(1000);
    }
    return 0;
}

while循环中，因为i = 0为初始条件，后置的i ++会先判断条件，i = 0不会执行while语句。将i++变成++i就好了

#include <windows.h>
#include <iostream.h>
#include <string>

using namespace std;

DWORD WINAPI countThread1(LPVOID argv);//声明一个线程函数
DWORD WINAPI countThread2(LPVOID argv);

int main(){
    //创建两个线程
//    int i = 0;
//    while(i < 50){
    HANDLE handle1 = CreateThread(NULL, 0, countThread1, NULL, 0, NULL);
//    HANDLE handle2 = CreateThread(NULL, 0, countThread2, NULL, 0, NULL);

    WaitForSingleObject(handle1, INFINITE);
//    WaitForSingleObject(handle2, INFINITE);

            //CreateThread(NULL, 0, countThread2, NULL, 0, NULL);
            //Sleep(50000);

//    }


    return 0;
}
//下面是两个线程函数
DWORD WINAPI countThread1(LPVOID argv){
    int i = 0;
    cout<<"i am in"<<endl;
    while(++i){
        if(10 == i)
            ExitThread(0);
        cout<<"this is thread2 and i = "<<i<<endl;
        Sleep(1000);
    }

    return 0;
}
DWORD WINAPI countThread2(LPVOID argv){
    int i = 0;
    while(++i){
        if(10 == i)
            ExitThread(0);
        cout<<"this is thread2 and i = "<<i<<endl;
        Sleep(1000);
    }
    return 0;
}

这里就会每秒输出，一条信息

ps:

WaitForSingleObject(handle1, INFINITE);现在要加上这条语句才可以。