int view_details(){
	clrscr();
	gotoxy(27,10);
	cout<<"enter employee number:";
	cin>>emp_id;
	EMPLOYEE s; //struct containing employee details
	ifstream f("emp.dat",ios::binary);
	f.seekg(0,ios::end);
	int t=f.tellg();
	t=t/sizeof(s);
	f.seekg(sizeof(s)*(emp_id-1));
	f.read((char *)&s, sizeof(s));
	if((strcmpi(s.name,"n/a")!=0)&&(strcmpi(s.fname,"n/a")!=0)
	 &&(strcmpi(s.dep,"n/a")!=0)&&emp_id<=t){
	  cout<<"name:"<<s.name<<endl;
	  cout<<"father's name:"<<s.fname<<endl;
	  cout<<endl<<"address:"<<s.addr<<endl;
	  cout<<endl<<"phone number:"<<s.phno<<endl;
	  cout<<endl<<"sex m/f:"<<s.s<<endl;
	  cout<<endl<<"date of birth:"<<s.dob[0]<<"/"<<s.dob[1]<<"/"<<s.dob[2]<<endl;
	  cout<<endl<<"department:"<<s.dep<<endl;
	  cout<<endl<<"salary:"<<s.sal<<endl;
	  cout<<"PRESS ANY KEY TO EXIT"<<endl;
	}
	else{
	  cout<<"invalid employee number"<<endl;
	  return 1;
	}
	f.close();
	return 0;
}
void del_emp(){
   clrscr();
   char ch='y';
   EMPLOYEE s; //struct containing employee details
   char chk;
   fstream f("emp.dat",ios::binary);
   while(ch=='y'||ch=='Y'){
	 if(view_details()!=1){
	   strcpy(s.name,"n/a");
	   strcpy(s.fname,"n/a");
	   strcpy(s.addr,"n/a");
	   strcpy(s.dep,"n/a");
	   s.s='i';
	   s.phno=0;
	   s.sal=0;
	   s.dob[0]=s.dob[1]=s.dob[2]=0;
	   cout<<"confirm delete?y/n:";
	   cin>>chk;
	   if(chk=='y'||chk=='Y'){
	 f.seekp(sizeof(s)*(emp_id-1));
	 f.write((char*)&s,sizeof(s));
	 cout<<"DELETED"<<endl;
	 f.close();
	   }
	 }
	 cout<<"wish to delete another employee? y/n:";
	 cin>>ch;
   }
   cout<<"PRESS ANY KEY TO EXIT";
   getch();
   main_menu();
}

void new_emp(){
  EMPLOYEE s;
  char chk='y';
  while(chk=='y'||chk=='Y'){
	fstream f("emp.dat",ios::binary);
	f.seekg(0,ios::end);
	int m=f.tellg()/sizeof(s)+1;  //(why?)
	s.accept();
	f.seekp(sizeof(s)*(m-1));
	f.write((char *)&s, sizeof(s));
	cout<<endl<<"the employee number is:"<<m<<endl;
	cout<<"wish to add another employee? y/n";
	cin>>chk;
	f.close();
  }
  main_menu();
}

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;


//your code would look sommat like
ifstream fin;
ofstream fout;
vector<string> filecontents;
fin.open("filename", fstream::binary);
/*
here you read the whole file into memory
i would suggest using the string library with
#include<string> and the STL vectors lib
with #include <vector> and then using the
getline function and a loop to grab a temp
string, check if it's at the EOF, and if not,
push_back the data into filecontents
*/
fin.close();
//modify the vector
fout.open("filename", fstream::trunc | fstream::binary);
/*
here you would simply need to fout all of the stuff, i'm sure
you can figure that out based on the code you have
*/