关键代码段

#include "stdafx.h"

#include <Windows.h>

#include <iostream>

#include <conio.h>

using namespace std;

DWORD WINAPI fun1(LPVOID lpParameter);

DWORD WINAPI fun2(LPVOID lpParameter);

int tickets=20;

CRITICAL_SECTION g_cs;

int _tmain(int argc, _TCHAR* argv[])

{

::InitializeCriticalSection(&g_cs);

HANDLE hThread1;

HANDLE hThread2;

hThread1=::CreateThread(NULL,0,fun1,NULL,0,NULL);

hThread2=::CreateThread(NULL,0,fun2,NULL,0,NULL);

::CloseHandle(hThread1);

::CloseHandle(hThread2);

::Sleep(4000);

::DeleteCriticalSection(&g_cs); //如果关键字段被删后 线程中再次申请 将出错

_getch();

return 0;

}

DWORD WINAPI fun1(LPVOID lpParameter)

{

while(1)

{

::EnterCriticalSection(&g_cs);

::Sleep(10);

if(tickets>0)

{

::Sleep(10);

cout<<"线程1出票"<<tickets--<<endl;

::LeaveCriticalSection(&g_cs);
//如果没有此句 关键段会一直被线程1掌控

}

else

{

::LeaveCriticalSection(&g_cs);

break;

}

::Sleep(1);
//实验操作与教材产生不同,如果此段新增代码不用 关键事件将被线程1垄断

}

return 0;

}

DWORD WINAPI fun2(LPVOID lpParameter)

{

while(1)

{

::EnterCriticalSection(&g_cs);

::Sleep(10);

if(tickets>0)

{

::Sleep(10);

cout<<"线程2出票"<<tickets--<<endl;

::LeaveCriticalSection(&g_cs);

}

else

{

::LeaveCriticalSection(&g_cs);

break;

}

::Sleep(1);

}

return 0;

}