我这到底是什么问题啊，求大佬解惑

#include<stdio.h>
#include<stdlib.h>
#define N 2
struct Student
{
int num;
char name[20];
float English;
float Math;
float Mazhe;
float Coupute;
float Technology;
}stu[N],stu1;void input()
{
int i;
for(i=0;i<N;i++)
{
printf("请输入第%d个同学的学号，姓名和成绩:",i+1);
scanf("%d%s%f%f%f%f%f",&stu[i].num,&stu[i].name,
&stu[i].English,&stu[i].Math,&stu[i].Mazhe,&stu[i].Coupute,&stu[i].Technology);
}
}
void PrintScore(float x)
{
int i,t;
for(i=0;i<N-1;i++)
for(t=0;t<N-i;t++)
if(stu[t].num>stu[t+1].num)
{
stu1=stu[t];
stu[t]=stu[t+1];
stu[t+1]=stu1;
}
for(i=0;i<N+1;i++)
printf("%d%s%f\n",stu[i].num,stu[i].name,stu[i].English);
}
int max()
{
int i,a,b;
float t[N];
for(i=0;i<N;i++)
t[i]=stu[i].English+stu[i].Math+stu[i].Mazhe+stu[i].Coupute+stu[i].Technology;
for(b=0;b<N;b++)
{
if(t[b]>t[b+1])
a=b;
}
return(a);
}
int main()
{
int t[N],i,j,a;
float b;
FILE *fp;
input(); for(i=0;i<N;i++)
t[i]=stu[i].English+stu[i].Math+stu[i].Mazhe+stu[i].Coupute+stu[i].Technology;
for(i=0;i<N-1;i++)
{
for(j=0;j<N-i;j++)
if(t[j]<t[j+1])
{
stu1=stu[j];
stu[j]=stu[j+1];
stu[j+1]=stu1;
}
}
if((fp=fopen("cj.dat","wb"))==NULL)
{
printf("cannot open file\n");
exit(0);
}
for(i=0;i<N+1;i++)
fprintf(fp,"%d%s %f %f %f %f %f\n",stu[i].num,stu[i].name,stu[i].English,
stu[i].Math,stu[i].Mazhe,stu[i].Coupute,stu[i].Technology);
printf("输出科目表：\n");
PrintScore(stu[0].English);
a=max();
b=t[a]/5;
printf("%d%s %f %f %f %f %f\n",stu[a].num,stu[a].name,
stu[a].English,stu[a].Math,stu[a].Mazhe,stu[a].Coupute,stu[a].Technology);
}