Summary
This chapter covers how constructors initialize object state and allocate resources when an object is created, and how destructors release resources and perform cleanup when an object’s lifetime ends.

General domain of usage
Resource management in object-oriented programming

#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>
#include <sstream>
#include <iostream>

class GradesManager {
public:
    GradesManager(int size);

    double calculateAverage();

    ~GradesManager();

private:
    int* grades;
    int size;
};

// ------------------- Tests -------------------

TEST_CASE("Average grade for size 5 should be 3", "[GradesManager]") {
    GradesManager manager(5); // grades: 1,2,3,4,5
    double avg = manager.calculateAverage();
    REQUIRE(avg == Approx(3.0));
}

TEST_CASE("Average grade for size 1 should be 1", "[GradesManager]") {
    GradesManager manager(1); // grades: 1
    double avg = manager.calculateAverage();
    REQUIRE(avg == Approx(1.0));
}

TEST_CASE("Average grade for size 10 should be 5.5", "[GradesManager]") {
    GradesManager manager(10); // grades: 1..10
    double avg = manager.calculateAverage();
    REQUIRE(avg == Approx(5.5));
}

TEST_CASE("Constructor output should print 'Grades initialized.'", "[GradesManager][output]") {
    std::ostringstream oss;
    std::streambuf* oldCout = std::cout.rdbuf(oss.rdbuf());

    GradesManager manager(3);

    std::cout.rdbuf(oldCout);
    REQUIRE(oss.str().find("Grades initialized.") != std::string::npos);
}

TEST_CASE("Destructor output should print 'Grades memory released.'", "[GradesManager][output]") {
    std::ostringstream oss;
    std::streambuf* oldCout = std::cout.rdbuf(oss.rdbuf());

    {
        GradesManager manager(2);
    } // destructor called here

    std::cout.rdbuf(oldCout);
    REQUIRE(oss.str().find("Grades memory released.") != std::string::npos);
}

test.cpp

Object-Oriented Programming (OOP) in C++ helps you build clean, reusable, and scalable code by organizing programs around objects and classes. You’ll learn how to define and use classes, create constructors and destructors, and apply encapsulation to protect data. Topics like inheritance, polymorphism, static members, access control, and operator overloading will help you design flexible and efficient code structures. 

Learn how to create classes and objects, define attributes and methods, work with static members and the this keyword. Gain a solid foundation in how objects interact and how to write clean, modular code using OOP principles.

Learn how constructors and destructors manage object creation and cleanup. Practice using initialization lists, constructor delegation, and writing clean, efficient code with proper object lifecycle handling.

Learn how encapsulation, one of OOP's core principles, improves code modularity and maintainability through data hiding, access control, and the use of accessor and mutator methods.

Learn about fundamental mechanism of object-oriented programming that enables code reuse and promotes the creation of hierarchical relationships among classes.

Polymorphism is a foundational concept in OOP that enables the creation of flexible and extensible code structures. You will learn about virtual function, abstract classes and operator overloading and their pivotal roles in promoting code flexibility and scalability.

Challenge: Managing Data with Constructors and Destructors

Example

Solution

Awesome!

Challenge: Managing Data with Constructors and Destructors

Example

Solution