How to Avoid Memory Leaks When Using a Vector of Pointers to Dynamically Allocated Objects in C++?

// C++ program demonstrating the use of unique_ptr with a vector of objects

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

// Define the MyClass class
class MyClass
{
  public:
    // Constructor that takes an integer value
    MyClass(int value) : value(value)
    {
        // Print message when constructor is called
        cout << "Constructor called for " << value << endl;
    }

    // Destructor
    ~MyClass()
    {
        // Print message when destructor is called
        cout << "Destructor called for " << value << endl;
    }

    // Getter for the value
    int getValue() const
    {
        return value;
    }

  private:
    // Private member variable to store the value
    int value;
};

int main()
{
    // Vector of unique pointers to MyClass objects
    vector<unique_ptr<MyClass>> vec;

    // Create 5 MyClass objects and add them to the vector
    for (int i = 0; i < 5; ++i)
    {
        vec.push_back(make_unique<MyClass>(i));
    }

    // Iterate over the vector and print the value of each MyClass object
    for (const auto &ptr : vec)
    {
        cout << "Value: " << ptr->getValue() << endl;
    }

    return 0;
}

// C++ program to demonstrate the use of raw pointers with vector

#include <iostream>
#include <vector>

using namespace std;

// Class definition
class MyClass
{
  public:
    // Constructor that initializes the value and outputs a message
    MyClass(int value) : value(value)
    {
        cout << "Constructor called for " << value << endl;
    }

    // Destructor that outputs a message
    ~MyClass()
    {
        cout << "Destructor called for " << value << endl;
    }

    // Getter function to access the value
    int getValue() const
    {
        return value;
    }

  private:
    // Data member to store the value
    int value;
};

int main()
{
    // Vector to store raw pointers to MyClass objects
    vector<MyClass *> vec;

    // Create and add MyClass objects to the vector
    for (int i = 0; i < 5; ++i)
    {
        // Create a new MyClass object and add it to the vector
        vec.push_back(new MyClass(i));
    }

    // Output the value of each MyClass object in the vector
    for (const auto &ptr : vec)
    {
        // Access and print the value using the pointer
        cout << "Value: " << ptr->getValue() << endl;
    }

    // Manually delete the MyClass objects to avoid memory leaks
    for (auto ptr : vec)
    {
        // Free the memory allocated for each MyClass object
        delete ptr;
    }

    return 0;
}

// C++ program to demonstrate the use of custom deleters with unique_ptr and vector

#include <iostream>
#include <memory>
#include <vector>

using namespace std;

// Class definition
class MyClass
{
  public:
    // Constructor that initializes the value and outputs a message
    MyClass(int value) : value(value)
    {
        cout << "Constructor called for " << value << endl;
    }

    // Destructor that outputs a message
    ~MyClass()
    {
        cout << "Destructor called for " << value << endl;
    }

    // Getter function to access the value
    int getValue() const
    {
        return value;
    }

  private:
    int value; // Data member to store the value
};

// Custom deleter function that outputs a message and deletes the object
void customDeleter(MyClass *ptr)
{
    cout << "Custom deleter called for " << ptr->getValue() << endl;
    // Free the memory allocated for the MyClass object
    delete ptr;
}

int main()
{
    // Vector to store unique_ptr with custom deleter
    vector<unique_ptr<MyClass, void (*)(MyClass *)>> vec;

    // Create and add MyClass objects to the vector using unique_ptr with a custom deleter
    for (int i = 0; i < 5; ++i)
    {
        vec.push_back(unique_ptr<MyClass, void (*)(MyClass *)>(new MyClass(i), customDeleter));
    }

    // Output the value of each MyClass object in the vector
    for (const auto &ptr : vec)
    {
        cout << "Value: " << ptr->getValue() << endl; // Access and print the value using the unique_ptr
    }

    // No need to manually delete objects as unique_ptr with custom deleter will handle it

    return 0;
}