Exercises: OOP & STL Challenge

Let's Think About This For a Second

This set is tougher than the warm-up, combining the class/object/constructor/access-specifier topics from the Advanced chapter with the pointer/reference/STL vector topics from the Intermediate chapter. The tasks involve designing a class like you would in production code, and handling pointers and memory addresses directly. Only look at the solution after trying it yourself first — bonus points if you can factor in some error-handling logic at this stage too.

Exercises

Task 1: Build a Book class with private members title (string) and price (double), along with a constructor and getter methods — then put 3 Book objects into a vector<Book> and display them with a loop. Task 2: Create an int variable and print its address using a pointer — then dereference (*) it to increase the value by 10 through the pointer, and confirm whether the original variable's value changed. Task 3: Put 10 integers into a vector<int>, then use a function that takes a reference parameter (vector<int>&) to double every value in the vector — check whether the original vector changed once the function returns.

• Wrote Task 1's Book class + vector<Book> loop display yourself
• Proved in Task 2 that pointer dereferencing changes the original variable's value
• Modified the vector from inside the function in Task 3 using a reference parameter and verified it

Example Code

#include <iostream>
#include <vector>
#include <string>
using namespace std;

class Book {
private:
    string title;
    double price;
public:
    Book(string t, double p) : title(t), price(p) {}
    string getTitle() const { return title; }
    double getPrice() const { return price; }
};

void doubleValues(vector<int>& nums) {
    for (int& n : nums) {
        n = n * 2;
    }
}

int main() {
    // Task 1
    vector<Book> books;
    books.push_back(Book("C++ Basics", 8.5));
    books.push_back(Book("STL Guide", 12.0));
    books.push_back(Book("OOP in Depth", 15.75));
    for (const Book& b : books) {
        cout << b.getTitle() << " - $" << b.getPrice() << "\n";
    }

    // Task 2
    int score = 90;
    int* ptr = &score;
    cout << "Address: " << ptr << ", Value: " << *ptr << "\n";
    *ptr += 10;
    cout << "Updated score: " << score << "\n";

    // Task 3
    vector<int> nums = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    doubleValues(nums);
    for (int n : nums) cout << n << " ";
    cout << "\n";

    return 0;
}

After running Task 2, you'll confirm that score's original value of 90 became 100 through pointer dereferencing; after running Task 3, you'll see that every value in the nums vector has doubled.