#include <iostream>
#include <windows.h>
#include <fstream>
#include <string>
using namespace std;
class Entry 
{
public:

    char name[50];
    int id;
    float sal;
    bool b;
     Entry *next;
     void clear(Entry *head,Entry *tail)
     {
         while(head!=NULL)
              {
                  head=tail->next;
                  delete tail;
                  tail=head;
              }
     }

};

int main ()
{
        ifstream myfile1;
        ofstream myfile2;
        char *buff="",temp[256]="";
        int i,length;
        Entry *head=NULL,*tail=NULL,*e=new Entry();

  do
  {
      cout<<"Enter ur  option"<<endl;
      cout<<"1.Load data into file"<<endl;
      cout<<"2.Save data into file"<<endl; 
      cout<<"3.Read data from file"<<endl;
      cout<<"4.Close the file"<<"\n";
      cin>>i;
      switch(i)
      {
      case 1:
            if(head==NULL)
            {
              head=tail=new Entry();
            }
            else
            {     
              if(head->next==NULL)
                 head->next=tail->next=new Entry();
              else
                 tail->next=new Entry();
              tail=tail->next;
            }
            if(head==tail)
            {
            head->next=tail->next=NULL;
            }
            cout<<"Enter name\t";
            cin>>tail->name;
            cout<<"Enter Id\t";
            cin>>tail->id;
            cout<<"Enter salary\t";
            cin>>tail->sal;
            cin.clear();
            cout<<"Enter Boolean value\t";
            cin>>tail->b;
            cin.clear();
            break;
       case 2:
            myfile2.open ("C:\\example.bin",ios::app|ios::in|ios::ate);
            tail=head;
            while(head!=NULL)
            {
              myfile2<<head->name<<"\t";
              myfile2<<head->id<<"\t";
              myfile2<<head->sal<<"\t";
                  if((head->b==false)||(head->b==true))
                  {
                      myfile2<<head->b<<"\n";
                      cin.clear();
                  }
              head=head->next;
            }
            myfile2.close();
            head=tail;
            e->clear(head,tail);
            break;
        case 3:
            myfile1.open("C:\\example.bin",ios::out|ios::ate);

            cout<<"the contents are:\n";

            myfile1.seekg(0,ios::end);
            length=myfile1.tellg();
            if(length>0)
            {
                myfile1.seekg(0,ios::beg);
                buff=new char[length];
                memset(buff,0,length);
                myfile1.read(buff,length);
                cout<<buff<<"\n";
            }
            else
            {
                cout<<"file is empty\n";
            }
            delete []buff;
            myfile1.close();
            break;
        case 4:
            if(head==NULL)
                e->clear(head,tail);
            delete e;
            exit(0);
        default:
            if(head==NULL)
                e->clear(head,tail);
            delete e;
            exit(0);
      }
  }while(1);

  return 0;
}

hi
Iam using fstreams to create a file with storing data of type string,integer,bool,float.once the file is created(C://..//example.txt) and enter the data and closed it.but when we open the file manually and modify it and save the file.But i don't want to change the file content manually.For that what can i do to my program.
the code is as follows....

can any one help me.
thanks in advance...

how we protect our files from others to modify them through programming

You can't on MS-Windows. About the best you can do is encrypt the files, then when your program need to change the file decript it again. If you are running a version of MS-Windows that has NTFS file system then you can protect the folder in which the files are located, but not the files themselves.