Searching a record in a data file :-

#include<iostream.h>
#include<conio.h>
#include<fstream.h>


class student
 {
  int roll;
  char name[15];
      public:
  void show()
      {
     cout<<"\nRoll :"<<roll<<endl;
     cout<<"\n Name :"<<name<<endl;
            }
      int ret_roll()
       {
          return(roll);
         }

  };
void main()
 {

  student s,x;
      int r,flag=0;
      cout<<"Enter the Roll No. to Perform Search: \n";
      cin>>r;
  ifstream fin("stu.dat");
      while(fin)
      {
          fin.read((char*)&s,sizeof s);
            if(s.ret_roll()==r)
             {
                x=s;
                  flag++;
                  break;
               }

   }
      if(flag!=0)
       {
          cout<<"Queried Record is as Follows :\n";
    cout<<"------------------------------------------------\n\n";
            x.show();
         }
      else
          cout<<"Queried Record does Not Exist. ";
  getch();
 }