How do I search in a file for book id

/*password is admin*/
#include <iostream>
#include <fstream>
#include <algorithm>
#include <string>

using namespace std;

void list_all_books_1();
void list_available_books_2();
void borrow_books_3();
void search_for_abook_4();
void add_new_book_5();
void delete_books_6();


char path[] = "library books.txt";

void output(){
	//this function for displaying choices only
	cout << "***********************************" << endl;
	cout << "1. List all books in library" << endl;
	cout << "2. List available books to borrow " << endl;
	cout << "3. Borrow a Book from library" << endl;
	cout << "4. Search For a Book" << endl;
	cout << "5. Add New Books" << endl;
	cout << "6. Delete a Book" << endl;
	cout << "7. EXIT The Library" << endl;
	cout << "***********************************" << endl;
}

//=====================================================================================================================================================

struct books{
	//identfying books with all needed things
	int id, status;
	string title, p_name, p_address;
	string date;
};
struct author{
	string aut_name;
	string aut_nationality;
};

//=====================================================================================================================================================

//function for choice 1 showing the books (under constructions)

void list_all_books_1(){
	ifstream show;
	char all;
	show.open(path, ios::in | ios::app);
	while (!show.eof()){
		show >> all;
		if (all == '%')
			cout << "\n\n";
		
		else if (all == '.')
			cout << "\n\n\n";
		
		else if (all == ' ')
			cout << " ";
		
		else
			cout << all;
	}
	cout << endl;
	show.close();
}

//=====================================================================================================================================================

void list_available_books_2(){

	//function for choice 2 (list available books to borrow)
}

//=====================================================================================================================================================

void borrow_books_3(){

	//function for choice 3( Borrow a Book )
}

//=====================================================================================================================================================

void search_for_abook_4(){
	ifstream search;
	int idx, i = 0,get;
	cout << "enter the ID of the book you're looking for";
	cin >> idx;
	search.open(path, ios::in | ios::app);
	while (!search.eof()){
		search >> get;
		if (idx == get)
			i++;
		else
			i = 0;
	}
	if (i > 0)
		cout << "found";
	else
		cout << "not found";
}

//=====================================================================================================================================================

//for choice 5 to fill books (under constructions)
void add_new_book_5(){
	fstream d_base;
	int aut_number, booksnumber;
	books newbook[1000];
	author aut[100];
	cout << "how many books you want to add ? ";
	cin >> booksnumber;
	cout << "what books you want to add :" << endl;
	d_base.open(path, ios::out | ios::app);
	for (int i = 0; i < booksnumber; i++){

		cout << "id please : "; cin >> newbook[i].id;
		cout << "title : ";				 cin.ignore();   getline(cin, newbook[i].title);
		cout << "publisher name :";						 getline(cin, newbook[i].p_name);
		cout << "publisher address : ";				     getline(cin, newbook[i].p_address);

		d_base << "[BOOK INFO]" << "%Book Id : " << newbook[i].id << "%title : " << newbook[i].title;
		d_base << "%[PUBLISHER INFO]" << "%publisher name : " << newbook[i].p_name << "%puplisher address :" << newbook[i].p_address;
		d_base << "%[AUTHOR(s) INFO]";

		cout << "how many authors for the books";
		cin >> aut_number;

		for (int j = 0; j < aut_number; j++){
			cout << "author" << j + 1 << " name : ";	cin.ignore();    getline(cin, aut[j].aut_name);
			cout << "Nationality : ";									 getline(cin, aut[j].aut_nationality);

			d_base << "% Authors Name : " << aut[j].aut_name << "% Nationality : " << aut[j].aut_nationality;
		}

		cout << "Publish date :";					    getline(cin, newbook[i].date);
		cout << "How many copies of " << newbook[i].title << " ";		cin >> newbook[i].status;

		d_base << "%[MORE INFO]";
		d_base << "%PublishedAt : " << newbook[i].date << "%status :" << newbook[i].status << "." << endl;
	}
	d_base.close();
	cout << "Books Have Been Saved Sucessfully";

}

//=====================================================================================================================================================

void delete_books_6(){

	//function for searching for a book

}

//=====================================================================================================================================================

int main(){
	string choice;
	cout << "welcome to FCIS library\n\n";

	do{
		output();
		cout << "what do you want to do ? ";
		getline(cin, choice);

		if (choice == "1"){
			list_all_books_1();
		}

		//this one for list available books
		else if (choice == "2"){

			//not completed

		}

		//this one for borrow a book
		else if (choice == "3"){

			//not completed yet don't choose 3

		}
		else if (choice == "4"){

			search_for_abook_4();

		}

		//this one is for adding new books to the list
		else if (choice == "5"){
			string pass;

			do{

				cout << "you must be an admin to add new books." << endl << "please enter passowrd (use small letters) : ";
				cin >> pass;

				if (pass == "b")
					break;

				else if (pass == "admin"){
					cout << "ACCESS GAINED	 WELCOME " << endl;

					add_new_book_5();
				}
				else{
					cout << "Wrong password try again or press (b) to try another choice";
					continue;
				}

			} while (pass != "admin");
		}

		//this one for deleteing a book
		else if (choice == "6"){

			//not completed yet

		}
		else if (choice == "7"){

			cout << "Thanks for Using FCIS LIBRARY" << endl;
			break;

		}
		else
			cout << "\nwrong choice please choose again\n\n";

	} while (true);

}