c

ofstream out; out.open("clientData.data",ios::ate); if(out.is_open()) {  BankData bd ={0,"","",0.0};  for(int i= 0;i<100;++i){   out.write(reinterpret_cast<const char*>(&bd),sizeof(bd));  } }

 BankData bd; cout<<"please num id 1-100"<<endl; cin>>bd.accountID;

 while(bd.accountID>0&&bd.accountID<=100){

  cout<<"input fist name , last name and balance"<<endl;  cin>>bd.firstName>>bd.lastName>>bd.balance;

  out.seekp((bd.accountID-1)*sizeof(bd));  out.write(reinterpret_cast<const char*>(&bd),sizeof(bd));

  cout<<"please num id 1-100"<<endl;  cin>>bd.accountID; }

 out.close();

 BankData bd; ifstream in("clientData.data"); if(!in) {  cerr<<"file not open"<<endl;  exit(1); }  cout<<" input num id to look"<<endl; cin>>bd.accountID;

 while(!in.eof()&&bd.accountID>0&&bd.accountID<101){    in.seekg((bd.accountID-1)*sizeof(bd));

  in.read(reinterpret_cast<char*>(&bd),sizeof(bd));    cout<<" first name ,last name , balance is:"<<bd.firstName<<"  "<<bd.lastName<<"  "<<bd.balance<<endl;      cout<<" input num id to look"<<endl;  cin>>bd.accountID;

 }

 in.close();