Xử lý file văn bản

/* File
  Bai tap 1.
- Nhap vao 1 day so nguyen co n so (2<n<10)
- Ghi day so vua nhap vao file Mang1.txt trong o E:\
- Tim gia tri lon nhat, ghi vao cuoi file Mang1.txt
- Doc du lieu trong file Mang1.txt
*/

#include<stdio.h>
#include<conio.h>

// khai bao
int a[10],n;
FILE *f;

// Nhap mang
void NhapMang(){
 printf("\n Nhap so phan tu ");
 do{ printf("\n n= ");
  scanf("%d",&n);
  if (n<2||n>10)
   printf("\n Nhap lai n!");
 }while (n<2||n>10);
 // Nhap day
 printf("\n Nhap day: ");
 for(int i=0;i<n;i++)
 {
  printf("\n a[%d]=",i); scanf("%d",&a[i]);
 }
}
// Ghi vao file
void GhiFile(){
 f=fopen("E:\\Mang1.txt","w");
 for(int i=0;i<n;i++)
 fwrite(&a[i],sizeof(int),1,f);

 fclose(f);
 printf("\n Da ghi xong!");

}
//Tim max
int Max(){
 int max=a[0];
 for(int i=1;i<n;i++)
 if(max<a[i]) max=a[i];

 return max;
}

// Ghi gia tri max vao file
void GhiMax(){
 f=fopen("E:\\Mang1.txt","a");
 // dua con tro file ve cuoi file
 fseek(f,SEEK_END,0);
 int max=Max();
 fwrite(&max,sizeof(int),1,f);

 fclose(f);
 printf("\n Da ghi xong gia tri Max !");
}

// doc du lieu tu file
void DocFile(){
 printf("\n Doc du lieu tu file: \n ");
 f=fopen("E:\\Mang1.txt","r");
 int t;
 for(int i=0;i<n;i++){
  fread(&t,sizeof(int),1,f);
  printf("%d ;",t);
 }
 // doc gia tri max
 fread(&t,sizeof(int),1,f);
   printf("\n Max: %d",t);
}

// Ham main
int main(){
 NhapMang();
 GhiFile();
 GhiMax();
 DocFile();
 getch();
 return 0;
}