Ogrenci vize-final

#include
#include
#include
#include
int a;
//----------------------------------------------------------------------------
void not_oku(void);
void kayit_yap(void);

int main()
{
printf("Ne yapmak istersiniz?\nNotlari okumak icin 1 girin.\nKayit yapmak icin 2 girin.\nProgrami kapatmak icin 3 girin:");scanf("%d", &a);
if(a==1)
{
not_oku();
}
if(a==3)
{
exit(0);
}
if(a==2)
{
kayit_yap();
}
return 0;
}

void not_oku(void)
{
char ch;
FILE *f;
f=fopen("C:\\notlar.txt","r");
ch=getc(f);

while (ch!=EOF){
putchar(ch);
ch=getc(f);
}

printf("\nKayit yapmak icin 2'i girin:");
scanf("%d", &a);
}

void kayit_yap(void)
{
struct ogrenci{
int vize;
int final;
char isim[25];
} ogrenci;
char buf[255];
FILE *adres; int ortalama;
adres=fopen("C:\\notlar.txt","a");

printf("Ogrenci vize notu:");
scanf("%d",&ogrenci.vize);
fprintf(adres,"Vize Notu: %d\n",ogrenci.vize);
printf("Final notunu girin:");
scanf("%d",&ogrenci.final);
fprintf(adres,"Final Notu: %d\n",ogrenci.final);
printf("Ogrenci adi:");
scanf("%s",&ogrenci.isim);
fprintf(adres,"Adi ve Soyadi: %s\n",ogrenci.isim);
ortalama=(ogrenci.vize+ogrenci.final)/2;
if(ortalama>=55)
fprintf(adres,"Durum:Gecti\n");
else
fprintf(adres,"Durum:Kaldi\n");
fprintf(adres,"**************************\n");

}