freopen("debug\\in.txt","r",stdin);
freopen("debug\\out.txt","w",stdout);
fclose(stdin);
fclose(stdout);
都表示些什么意思？
还有下面的程序为什么闪一下就结束了：
#include <stdio.h>
int main()
{
int a,b;
freopen("debug\\in.txt","r",stdin);  
freopen("debug\\out.txt","w",stdout);
while(scanf("%d %d",&a,&b)!=EOF)
        printf("%d\n",a+b);
fclose(stdin);
fclose(stdout);
system ("pause");
return 0;
}