Будьте так добры (найти ошибку в коде)

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <conio.h>
 
 
using namespace std;
 
struct student {
    char name[4];
    char lastname[4];
    int age;
 
    };
 
 
  int main( )
{
    const int r=1;
    student A[r];
  FILE *Ptr;
  int k;
  if(( Ptr=fopen("mass1.txt","rt"))!=NULL)
 { cout<<"File est, nuzhno vvecni novie dannie?, 1-yes,drugie-No";
      cin>>k;
  if(k==1){ 
 Ptr=fopen("mass1.txt","wt");
  fprintf(Ptr,"Name    Last     Age  \n");
 
  for(int n=0;n<r;n++){
       Ptr=fopen("mass1.txt","at");
fprintf(Ptr," \n ");
  printf("Enter Name %d",n+1);
  printf(":  \n");
 cin>>A[n].name;
  printf("Enter lastname %d",n+1);
  printf(":  \n");
   cin>>A[n].lastname;
 printf("Enter Age %d",n+1);
  printf(":  \n");
  scanf("%d",&A[n].age);
  fputs(A[n].name,Ptr);
  fprintf(Ptr,"    ");
  fputs(A[n].lastname,Ptr);
  fprintf(Ptr,"   ");
  fprintf(Ptr,"%d        ",A[n].age);
   Ptr=fopen("mass2.bin","wb+");
const char *a;
a=&A[n].name;
const int *b;
b=&A[n].age;
const char *c;
c=&A[n].lastname;
fwrite(a,sizeof(a),1,Ptr);
fwrite(b,sizeof(b),1,Ptr);
fwrite(c,sizeof(c),1,Ptr);
 Ptr=fopen("mass3.rec","wb");
 fwrite(a,sizeof(a),1,Ptr);
fwrite(b,sizeof(b),1,Ptr);
fwrite(c,sizeof(c),1,Ptr);
 system("cls");
  }
  
        
fclose(Ptr);
  return 0;}else {
      
      Ptr=fopen("mass1.txt","rt");
   while(!feof(Ptr))
        {
            cout << char(fgetc(Ptr)) << " ";
 
   } fclose(Ptr);}}
  else
  {
  Ptr=fopen("mass1.txt","wt");
  fprintf(Ptr,"  Name     Lastname      Age \n");
 
  for(int n=0;n<r;n++){
       Ptr=fopen("mass1.txt","at");
fprintf(Ptr," \n ");
  printf("Enter Name %d",n+1);
  printf(":  \n");
 cin>>A[n].name;
  printf("Enter Lastname %d",n+1);
  printf(":  \n");
   cin>>A[n].lastname;
 printf("Enter Age %d",n+1);
  printf(":  \n");
  scanf("%d",&A[n].age);
  fputs(A[n].name,Ptr);
  fprintf(Ptr,"     ");
  fputs(A[n].lastname,Ptr);
  fprintf(Ptr,"    ");
  fprintf(Ptr,"%d       ",A[n].age);
   Ptr=fopen("mass2.bin","wb+");
const char *a;
a=&A[n].name;
const int *b;
b=&A[n].age;
const char *c;
c=&A[n].lastname;
fwrite(a,sizeof(a),1,Ptr);
fwrite(b,sizeof(b),1,Ptr);
fwrite(c,sizeof(c),1,Ptr);
 Ptr=fopen("mass3.rec","wb");
 fwrite(a,sizeof(a),1,Ptr);
fwrite(b,sizeof(b),1,Ptr);
fwrite(c,sizeof(c),1,Ptr);
 system("cls");
  }
fclose(Ptr);}
}