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PostThreadMessage的原型是這樣的

BOOL PostThreadMessage( DWORD idThread,
     UINT Msg,
     WPARAM wParam,
     LPARAM lParam
);

PostThreadMessage可以用于線程之間的異步通訊，因?yàn)樗挥玫却{(diào)用者返回，
這也許是線程通訊中最簡單的一種方法了。

但是要注意以下問題
1 .PostThreadMessage有時(shí)會失敗，報(bào)1444錯誤(Invalid thread identifier. )
其實(shí)這不一定是線程不存在的原因，也有可能是線程不存在消息隊(duì)列(message queue)造成的。
事實(shí)上，并不是每個(gè)thread都有message queue,那如何讓thread具有呢？
答案是，至少調(diào)用message相關(guān)的function一次，比如GetMessage,PeekMessage。

2.如果是post動態(tài)分配的memory給另外一個(gè)thread,要注意內(nèi)存的正確釋放。

3.PostThreadMessage不能夠post WM_COPYDATE之類的同步消息，否則會報(bào)錯

4.最好不要使用PostThreadMessage post message給一個(gè)窗口,使用PostMessage替代。

下面是我寫的一個(gè)比較嚴(yán)整的例子，僅供參考。

#include <windows.h>
#include <cstdio>
#include <process.h>

#define MY_MSG WM_USER+100
const int MAX_INFO_SIZE = 20;

HANDLE hStartEvent; // thread start event

// thread function
unsigned __stdcall fun(void *param)
{
     printf("thread fun start

\n");

     MSG msg;
     PeekMessage(&msg, NULL, WM_USER, WM_USER, PM_NOREMOVE);

    if(!SetEvent(hStartEvent)) //set thread start event
     {
         printf("set start event failed,errno:%d\n",::GetLastError());
        return 1;
     }
    
    while(true)
     {
        if(GetMessage(&msg,0,0,0)) //get msg from message queue
         {
            switch(msg.message)
             {
            case MY_MSG:
                char * pInfo = (char *)msg.wParam;
                 printf("recv %s\n",pInfo);
                 delete[] pInfo;
                break;
             }
         }
     };
    return 0;
}

int main()
{
     HANDLE hThread;
     unsigned nThreadID;

     hStartEvent = ::CreateEvent(0,FALSE,FALSE,0); //create thread start event
    if(hStartEvent == 0)
     {
         printf("create start event failed,errno:%d\n",::GetLastError());
        return 1;
     }

    //start thread
     hThread = (HANDLE)_beginthreadex( NULL, 0, &fun, NULL, 0, &nThreadID );
    if(hThread == 0)
     {
         printf("start thread failed,errno:%d\n",::GetLastError());
         CloseHandle(hStartEvent);
        return 1;
     }

    //wait thread start event to avoid PostThreadMessage return errno:1444
     ::WaitForSingleObject(hStartEvent,INFINITE);
     CloseHandle(hStartEvent);

    int count = 0;
    while(true)
     {
        char* pInfo = new char[MAX_INFO_SIZE]; //create dynamic msg
         sprintf(pInfo,"msg_%d",++count);
        if(!PostThreadMessage(nThreadID,MY_MSG,(WPARAM)pInfo,0))//post thread msg
         {
             printf("post message failed,errno:%d\n",::GetLastError());
             delete[] pInfo;
         }
         ::Sleep(1000);
     }

     CloseHandle(hThread);
    return 0;
}