Can anyone please this line, if y == totalBook-1 then print book not found. This is a library management system and this code is for searching a book. I just dont get the y == totalBook-1 how does it work?

if(totalBook!=0){
        cout<<"Enter the book ID you want to search: ";
        cin>>id;
        for(int y=0; y<totalBook; y  ){
            if(id==bookID[y]){
                cout<<"Book found!"<<endl;
                cout<<endl;
                cout<<"Book name: "<<bookName[y]<<endl;
                cout<<"Book author: "<<bookAuthor[y]<<endl;
                cout<<"Book ID: "<<bookID[y]<<endl;
                cout<<endl;
                break;
            }if(y == totalBook-1){
                cout<<endl;
                cout<<"Book not found!"<<endl;
                cout<<endl;

Heres the full code

#include<iostream>
#include<stdlib.h>
using namespace std;

int main(){
    char yesNo;
    string bookName[50];
    string bookAuthor[50];
    string bookID[50];
    int totalBook=0, choice; //for case 1
    string id; // for case 2 and 3
    int j; //case 2
    do{
    system("CLS");
    cout << "==========================" << endl;
    cout << "LIBRARY MANAGEMENT SYSTEM" << endl;
    cout << "==========================" << endl;
    cout << "[1] Add Books" << endl;
    cout << "[2] Delete Books" << endl;
    cout << "[3] Search Books" << endl;
    cout << "[4] View Book List" << endl;
    cout << "[5] Close Application" << endl;
    cout<<"Enter a number: ";
    cin>>choice;
    switch(choice){
    case 1: // add book
        if(totalBook<50){
        cin.ignore();
        cout<<"Enter book name: ";
        getline(cin, bookName[totalBook]);
        cout<<"Enter book author: ";
        getline(cin, bookAuthor[totalBook]);
        cout<<"Enter book ID: ";
        getline(cin, bookID[totalBook]);
        totalBook  ;
        cout<<"Book succesfully added!"<<endl;
        }else{
            cout<<"Library is full!"<<endl;
        }
        break;
    case 2: //delete a book
        
        if(totalBook!=0){
        cout<<"Enter the book ID you want to delete: ";
        cin>>id;
        for(int y=0; y<totalBook; y  ){
            if(id==bookID[y]){
                for(j=y; j<totalBook; j  )
                bookID[j]=bookID[j 1];
                bookName[j]=bookName[j 1];
                bookAuthor[j]=bookAuthor[j 1];
                totalBook--;
                cout<<"Book deleted succesfully"<<endl;
                cout<<endl;
                break;
            }else if(y == totalBook-1){
                cout<<endl;
                cout<<"Book not found!"<<endl;
                cout<<endl;
            }}
        }else{
                cout<<"The library is empty!"<<endl;
            }
        break;
    case 3: // search book
        if(totalBook!=0){
        cout<<"Enter the book ID you want to search: ";
        cin>>id;
        for(int y=0; y<totalBook; y  ){
            if(id==bookID[y]){
                cout<<"Book found!"<<endl;
                cout<<endl;
                cout<<"Book name: "<<bookName[y]<<endl;
                cout<<"Book author: "<<bookAuthor[y]<<endl;
                cout<<"Book ID: "<<bookID[y]<<endl;
                cout<<endl;
                break;
            }if(y == totalBook-1){
                cout<<endl;
                cout<<"Book not found!"<<endl;
                cout<<endl;
                break;
            }}
        }else{
                cout<<"The library is empty!"<<endl;
            }
            break;
        
    case 4: // display all the books
        if(totalBook!=0){
        cout<<endl;
        cout<<"===================="<<endl;
        cout<<"All Books Available"<<endl;
        cout<<"===================="<<endl;
        cout<<endl;
        for(int y=0; y<totalBook; y  ){
      
          cout<<"Book name: "<< bookName[y] << endl;
          cout<<"Book author: "<< bookAuthor[y] << endl;
          cout<<"Book ID: "<< bookID[y] << endl;
          cout<<endl;
      }  
        }else{
            cout<<"The library is empty!"<<endl;
        }break;
    case 5:
        cout<<"Thank You!";
        exit(0);


    }cout<<"Do you want to continue (Y/N): ";
    cin>>yesNo;
    }while (yesNo == 'y' || yesNo == 'Y');
        cout<<"Thank You!";

    return 0;
}

CodePudding user response：

If the book is available in the system, the program will exit the for loop. The last value that will be assigned to y will be totalBook - 1 since y < totalBook. If at that point, book could not be found, the text Book not found will be printed.