help！！！！！！！！一词之差。cout和printf互换怎么结果这么大相差。

[guozhuyz]

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

DWORD WINAPI ThreadProc(LPVOID lpParam)
{
int i=0;
while (i<20)
{
cout<<"I am from a Thread,count="<<i++<<endl;
}
return 0;
}

int main()
{
HANDLE hThead;
DWORD dwTheadID;
//创建一个线程
hThead=CreateThread(
NULL,
NULL,
ThreadProc, //进程入口地址
NULL,
0, //指定线程立即运行
&dwTheadID);
//为什么这个cout不行，而换成printf（"Now another thread has been created. ID=%d\n",dwTheadID）
//却可以输出正确的。
//在此处换cout和printf[/color[/color]]
cout<<"Now another thread has been created. ID="<<dwTheadID<<endl;
//等待新线程运行结束。
::WaitForSingleObject(hThead,INFINITE);
::CloseHandle(hThead);
return 0;
}
使用cout的输出结果
Now anothI am from a Threer thread has beenad,count=0
I am fr created. ID=3592
om a Thread,count=1
I am from a Thread,count=2
I am from a Thread,count=3
I am from a Thread,count=4
I am from a Thread,count=5
I am from a Thread,count=6
I am from a Thread,count=7
I am from a Thread,count=8
I am from a Thread,count=9
I am from a Thread,count=10
I am from a Thread,count=11
I am from a Thread,count=12
I am from a Thread,count=13
I am from a Thread,count=14
I am from a Thread,count=15
I am from a Thread,count=16
I am from a Thread,count=17
I am from a Thread,count=18
I am from a Thread,count=19
Press any key to continue

printf的输出结果

Now another thread has been created. ID=2852
I am from a Thread,count=0
I am from a Thread,count=1
I am from a Thread,count=2
I am from a Thread,count=3
I am from a Thread,count=4
I am from a Thread,count=5
I am from a Thread,count=6
I am from a Thread,count=7
I am from a Thread,count=8
I am from a Thread,count=9
I am from a Thread,count=10
I am from a Thread,count=11
I am from a Thread,count=12
I am from a Thread,count=13
I am from a Thread,count=14
I am from a Thread,count=15
I am from a Thread,count=16
I am from a Thread,count=17
I am from a Thread,count=18
I am from a Thread,count=19
Press any key to continue
为什么会出现这样的问题？

[星羽]

试了，都是正确的，不果你最好这样写吧

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

DWORD WINAPI ThreadProc(LPVOID lpParam) 
{ 
    int i=0; 
    while (i <20) 
    { 
        cout <<"I am from a Thread,count=" <<i++ <<endl; 
    } 
    return 0; 
} 

int main() 
{ 
    HANDLE hThead; 
    DWORD dwTheadID; 
    //创建一个线程 
    cout <<"Now another thread has been created. ID=" <<dwTheadID <<endl; 
    hThead=CreateThread( 
        NULL, 
        NULL, 
        ThreadProc,       //进程入口地址 
        NULL, 
        0,               //指定线程立即运行 
        &dwTheadID); 
    //为什么这个cout不行，而换成printf（"Now another thread has been created. ID=%d\n",dwTheadID） 
    //却可以输出正确的。 
    //在此处换cout和printf[/color[/color]] 

    //等待新线程运行结束。 
    ::WaitForSingleObject(hThead,INFINITE); 
    ::CloseHandle(hThead); 
    return 0; 
} 

[珍惜生命远离CPP]

用_beginthreadex创建线程
再试试

使用CreateThread创建线程,有莫名其妙的问题比较正常

[过去的我]

printf也会出错,因为那句语句不是一个原子操作吧,
把打印threadid 的任务放到WaitForSingleObject后面比较好

[abupie]

printf应该是原子操作。
cout只输出到流导致吧，要查查cout实现。

[珍惜生命远离CPP]

是因为标准库是有缓冲的.
你用没有缓冲的输出试试.

[过去的我]

这是我测试的printf
I am from a Thread,count=2
I am from a Thread,count=3
I am from a Thread,count=4
I am from a Thread,count=5
I am from a Thread,count=6
I am from a Thread,count=7
I am from a Thread,count=Now another thread has been created. ID=2208
8
I am from a Thread,count=9
I am from a Thread,count=10
I am from a Thread,count=11
I am from a Thread,count=12
I am from a Thread,count=13
I am from a Thread,count=14
I am from a Thread,count=15
I am from a Thread,count=16
I am from a Thread,count=17
I am from a Thread,count=18
I am from a Thread,count=19

也会出错,因该不是原子操作

[晨星]

个人觉得没啥好奇怪的。printf和cout的内部实现不一样是完全可能的。
既然可能不一样，那么在多线程且未加锁的情况下结果不一样也是完全正常的。

[guozhuyz]

谢谢各位了。又学了不少东西。