win32多线程编程与锁

模拟售票程序。

未加锁程序：

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

int index = 0;
int ti = 100;

DWORD WINAPI fun1(
          LPVOID lpParameter
          );
DWORD WINAPI fun2(
          LPVOID lpParameter
          );
void main()
{
  HANDLE hthread1;
  hthread1 = CreateThread(NULL,0,fun1,NULL,0,NULL);
  CloseHandle(hthread1);
  HANDLE hthread2;
  hthread2 = CreateThread(NULL,0,fun2,NULL,0,NULL);
  CloseHandle(hthread2);

  Sleep(4000);//这样主线程不占用CPU
  
}

DWORD WINAPI fun1(
          LPVOID lpParameter
          )
{
  while(true)
  {
    
    if (ti>0)
    {
      
      ti--;
      cout<<"thread 11111:"<<ti<<endl;
      
    }
    else
      break;
  
    
  }
    
  return 0;
}
DWORD WINAPI fun2(
          LPVOID lpParameter
          )
{
  while(true)
  {
  
    if (ti>0)
    {
      
      ti--;
      cout<<"thread 22222:"<<ti<<endl;
      Sleep(5);
      
    }
    else
      break;
  
    
  }
  return 0;
}

加锁程序：

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

int index = 0;
int ti = 100;
HANDLE hmutex;//锁
DWORD WINAPI fun1(
          LPVOID lpParameter
          );
DWORD WINAPI fun2(
          LPVOID lpParameter
          );
void main()
{
  HANDLE hthread1;
  hthread1 = CreateThread(NULL,0,fun1,NULL,0,NULL);
  CloseHandle(hthread1);
  HANDLE hthread2;
  hthread2 = CreateThread(NULL,0,fun2,NULL,0,NULL);
  CloseHandle(hthread2);
  hmutex = CreateMutex(NULL,TRUE,NULL);
//  WaitForSingleObject(hmutex,INFINITE);
  ReleaseMutex(hmutex);
  Sleep(4000);//这样主线程不占用CPU
  
}

DWORD WINAPI fun1(
          LPVOID lpParameter
          )
{
  while(true)
  {
    WaitForSingleObject(hmutex,INFINITE);
    if (ti>0)
    {
      
      ti--;
      cout<<"thread 11111:"<<ti<<endl;
      
    }
    else
      break;
    ReleaseMutex(hmutex);
    
  }
    
  return 0;
}
DWORD WINAPI fun2(
          LPVOID lpParameter
          )
{
  while(true)
  {
    WaitForSingleObject(hmutex,INFINITE);
    if (ti>0)
    {
      
      ti--;
      cout<<"thread 22222:"<<ti<<endl;
      Sleep(5);
      
    }
    else
      break;
    ReleaseMutex(hmutex);
    
  }
  return 0;
}

可以根据运行结果比较区别，未加锁程序显然存在BUG，多次售同一张票。