Си++. Сортировка данных из файла

[vadima]

привет!!! у миня задача на структуру даних!!! нужна ввести дание в конце даних есть оценка нада ети дание сортувати за оценкой !!!
незнаю в чем проблема!!!
помогите плизззз!!!

#include <iostream.h>
#include <conio.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <iomanip.h>
struct institut
{
char inst[20];
char fac[20];
char spec[10];
int plan ;
int bal;
int hold;
int stnum;
};

int i,j;
FILE *fp;
//************************************
void input()
{
//float bal;
institut vuz[10];

int zak_vvedenia;

if (fp!=NULL)
remove("fp.dat");
else
{
fp=fopen("fp.dat","wb");
i=0;
do
{
cout<<"institut"<<endl;
cin>>vuz[i].inst;
cout<<"facultet"<<endl;
cin>>vuz[i].fac;
cout<<"specialnist"<<endl;
cin>>vuz[i].spec;
cout<<"plan priomu"<<endl;
cin>>vuz[i].plan;
cout<<"prohidnii bal"<<endl;
cin>>vuz[i].bal;


j=0;
{
//***************************

j++;

} ;


cout<<"contunue input? y/n"<<endl;

zak_vvedenia=getch();
fwrite(&vuz[i],sizeof(institut),1,fp);

i++;
}
while(zak_vvedenia!='n');
fclose(fp);
}
getch();
}
void read_from_file()
{
institut vuz;
//subject predmet;
if (!(fp=fopen("fp.dat","rb")))
cerr<<"file do not exist!";
else
{
cout<<setw(20)<<"it is file:"<<endl;
//fread(&predmet,sizeof(subject),1,fp);
fread(&vuz,sizeof(institut),1,fp);
while (!feof(fp))
{
cout<<"----institut------fakultet-----specialnist-----plan priomu-----prohid bal--"<<endl;
cout.setf(ios::left+3);
//*****************************************
cout<<setw(12)<<vuz.inst<<setw(12)<<vuz.fac<<setw(14)<<vuz.spec<<setw(20)<<vuz.plan<<setw(12)<<vuz.bal<<endl;

for(j=0;j<vuz.stnum;j++)

{
cout.setf(ios::left);

}
fread(&vuz,sizeof(institut),1,fp);

}
fclose(fp);
}
getch();
}
//***************************sort*******************************
void sort() {
float sr[10];
institut vuz[10];
if(!(fp=fopen("fp.dat","rb"))) cerr<<"file do not exist!";
else
{ i=0;
fread(&vuz,sizeof(institut),1,fp);
while(!feof(fp))
{
sr[i]=0;
for(j=0;j<vuz[i].stnum;j++)
sr[i]+=vuz[i].bal;
sr[i]=float(sr[i])/vuz[i].stnum;
i++;
fread(&vuz,sizeof(institut),1,fp);
}
fclose(fp);
int prep=i;
cout<<"subject\'s average ball"<<endl;
for(i=0;i<prep;i++)
{
cout.setf(ios::left);
cout<<setw(10)<<vuz[i].bal<<setw(5)<<sr[i]<<endl;
}
cout<<"subject with the highest ball: "<<endl;
float max=sr[0];
int predmet=0;
for(i=1;i<prep;i++)
if (max<sr[i])
{
max=sr[i];
predmet=i;
}
cout<<"max ball="<<max;
}
getch();
}
//*********************************************************
void main() {
while(1) { clrscr();
cout<<"     MENU \n"<<endl;
cout<<"1.vvedenia institutu"<<endl;
cout<<"2.chitati informaciu"<<endl;
cout<<"3.sort"<<endl;
//cout<<"4.view student database"<<endl;
//cout<<"5.list of subject with the highest ball"<<endl;
//cout<<"6.stypend"<<endl;
//cout<<"7.stypend found"<<endl;*/
cout<<"8.exit"<<endl;
cout<<endl;
int key;
cout<< "chosed menu item:";
cin>>key;
switch(key)
{
case 1: {input(); break;}
case 2: {read_from_file();break;}
case 3: {sort();break;}
//case 4: {list_student();break;}
//case 5: {maxbal();break;}
//case 6: {stipendia();break;}
//case 7: {fond();break;}
case 8: {exit(0);break;}
defaut: {cout<<"try anazer time...";getch();break;}
}
}
}