关于多线程问题

#include<stdio.h>
#include<Windows.h>
int num=0;
CRITICAL_SECTION gs;
DWORD WINAPI ThreadProc(LPVOID lpParam)
{
    int ntmp=0;
    for(int i=0;i<10;i++)
    {
        EnterCriticalSection(&gs);
        ntmp=num;
        ntmp++;
        Sleep(1);
        num=ntmp;
        LeaveCriticalSection(&gs);
    }
    return 0;
}
int main(int argc,char*argv[])
{
    InitializeCriticalSection(&gs);
    HANDLE hThread[10]={0};
    for( int i=0;i<10;i++)
    {
        hThread[i]=CreateThread(NULL,0,ThreadProc,NULL,0,NULL);
        if(hThread[i]=NULL)
        {
            printf("%d createthread error \r\n",i);
        }
    }
    WaitForMultipleObjects(10,hThread,TRUE,INFINITE);
    printf("%d \r\n",num);
    for(i=0;i<10;i++)
    {
        CloseHandle(hThread[i]);
    }
    DeleteCriticalSection(&gs);
    return 0;
}
我的电脑输出时0，但是书上说结果应该是100，哪位高手能帮小弟看看？