临界区示例

#include "stdafx.h"
#include <afxwin.h>
#include <windows.h>

CRITICAL_SECTION g_cs;
char g_cArray[10];

UINT ThreadProcFirst(LPVOID pParam);
UINT ThreadProcSecond(LPVOID pParam);

int main(int argc, char* argv[])
{
    InitializeCriticalSection(&g_cs);
    
    /*注意: 线程First与线程Second启动顺序不定*/
    AfxBeginThread(ThreadProcFirst, NULL);
    AfxBeginThread(ThreadProcSecond, NULL);
    
    Sleep(300);
    /*Sleep(1000);*/

    CString strResult = CString(g_cArray);
    AfxMessageBox(strResult);
    return 0;
}

UINT ThreadProcFirst(LPVOID pParam)
{
    EnterCriticalSection(&g_cs);
    printf("First");
    for (int i = 0; i < 10; ++i)
    {
        g_cArray[i] = 'a';
        Sleep(1);
    }
    
    LeaveCriticalSection(&g_cs);
    return 0;
}

UINT ThreadProcSecond(LPVOID pParam)
{
    EnterCriticalSection(&g_cs);
    printf("Second");
    for (int i = 0; i < 10; ++i)
    {
        g_cArray[10-i-1] = 'b';
        Sleep(1);
    }
    
    LeaveCriticalSection(&g_cs);
    return 0;
}


结果1：

FirstSecond

bbbbbbbbbb

结果2:

FirstSecond

aaaabbbbbb

结果3:

SecondFirst

aaaaaaaaaa

根据Sleep()的延迟结果可能不同.

当Sleep(1)时, 结果可能为 空 或者 a 或者 b 或者 其他值.