我按老师做法输入
#include <stdio.h>
void main()
{
int i,n,g;
i=0;
while(i<=50)
{
scanf("%d %d\n",&n,&g);
if(g>=80)
printf("%d %d\n",n,g);
i=i+1;
}
}

可是打入学号和成绩后发现无效，请问这是为什么？

#include <stdio.h>
void main()
{
int i,n,g;
i=0;
while(i<=50)
{
scanf("%d %d",&n,&g);
if(g>=80)
printf("%d %d\n",n,g);
i=i+1;
}
}

2楼真是强人.!

#include<iostream>
using namespace std;
class XS
{
public:
    int xh;
    int cj;
};
void main()
{
    int i;
   XS xs[5];
   for(i=0;i<5;i++)
      {
       cout<<"input xh please:"<<endl;
       cin>>xs[i].xh;
       cout<<"input cj please:"<<endl;
       cin>>xs[i].cj;
   }
     for(i=0;i<5;i++)
         if(xs[i].cj>80)
             cout<<"score:"<<xs[i].cj;
             cout<<"NO. is:"<<xs[i].xh<<endl;
}

#include<iostream>
using namespace std;
class XS
{
public:
    int xh;
    int cj;
};
void main()
{
    int i,k=0;
   XS xs[50];
   for(i=0;i<50;i++)
      {
       cout<<"input xh please:"<<endl;
       cin>>xs[i].xh;
       cout<<"input cj please:"<<endl;
       cin>>xs[i].cj;
   }
     for(i=0;i<50;i++)
     {
         if(xs[i].cj>80)
         {
             cout<<"score:"<<xs[i].cj;
             cout<<"NO. is:"<<xs[i].xh<<endl;
             k++;
         }
     }
     if(k==0)
         cout<<"there is no score above 80";
}