Smart Pointers In C++

In the C++ programming language, smarcpp tutorialers are class templates that are provided in the standard library (<memory>) that automatically manage the dynamically allocated memory. They act as wrappers around raw pointers but come up with the underlying memory management. These pointers are mainly used as templates so we can make a smarcpp tutorialer to any type of memory.

Smarcpp tutorialers help to prevent several general memory issues in C++ programming . Some issues are as follows:

• ✅ Memory leaks
• ✅ Dangling pointers
• ✅ Double deletion
• ✅ Unmanaged resources

Smarcpp tutorialers follow the RAII (resource acquisition initialization) principle, which means that memory is automatically acquired and released. We will implement smarcpp tutorialers such that they will release the memory of unused resources. First, we have to create a class with a pointer , overloaded operators(->, *) and destructors . After that, the destructor will be automatically called when its object goes out of the scope, and automatically, the dynamically allocated memory will be deleted.

Smart Pointers Example in C++

Let us take an example to illustrate the smarcpp tutorialer in C++.

Example

#include <iostream>  

using namespace std;    //using standard namespace

class SmartPtr { // Create the class to implement smart Pointer  

    int* ptr; // Actual pointer  

public:  

// Create an explicit constructor   

    explicit SmartPtr(int* p = NULL) { ptr = p; }  

      // Destructor to deallocate the resource used   

    ~SmartPtr() { delete (ptr); }  

      // Overloading dereferencing operator  

    int& operator*() { return *ptr; }  

};  

  int main()    //main function

{  

    SmartPtr ptr(new int());  

    *ptr = 100;  

    cout << *ptr;  

      // We don't need to call delete ptr: when the object  

    // ptr goes out of scope, the destructor for it is automatically  

    // called, and destructor does delete ptr.  

    return 0;  

}

Output:

Explanation:

In this example, we demonstrate a smarcpp tutorialer using a custom SmartPtr class. It manages a dynamically allocated integer by automatically deallocating memory in its destructor, which prevents memory leaks. After that, the overloaded * operator allows access to the pointed value like a regular pointer.

Smart Pointer Example in C++ using Template Class

The above example works only for int. Now, we will create a template that will work for every data type . Let us take another example to illustrate the smarcpp tutorialer in C++ using a template class.

Example

#include <iostream>  

using namespace std;     //using standard namespace

  template <class T> // Create a template class   

class SmartPtr {  

    T* ptr; // Actual pointer  

public:  

    // Constructor  

    explicit SmartPtr(T* p = NULL) { ptr = p; }  

      // Destructor  

    ~SmartPtr() { delete (ptr); }  

    // Overloading dereferencing operator  

    T& operator*() { return *ptr; }  

    // Overloading arrow operator so that  

    // members of T can be accessed  

    // like a pointer

    T* operator->() { return ptr; }  

};  

int main()    //main function

{  

    SmartPtr<int> ptr(new int());  

    *ptr = 100;  

    cout << *ptr;  

    return 0;  

}

Output:

Explanation:

In this example, we define a generic smarcpp tutorialer class SmartPtr using C++ templates, which allows it to manage dynamically allocated objects of any type. After that, it automatically deletes the resource in its destructor, which helps to prevent memory leaks. The overloaded * and -> operators enable pointer-like behavior for accessing and modifying the object.

Types of Smart Pointers

There are several smarcpp tutorialers in C++. Some of them are as follows:

Unique_ptr

The uniqueptr is a smarcpp tutorialer that ensures that only one uniqueptr can own a specific resource at any given time, which prevents memory leaks and unpredictable behavior. It indicates that the associated resource is automatically deallocated when the unique_ptr exits its scope or is manually removed using the move method.

Syntax:

It has the following syntax:

std::unique_ptr<Type> ptr(new Type(args));

Features of Unique_ptr in C++

Several features of unique_ptr in C++ are as follows:

• ✅ It particularly owns a resource.
• ✅ It cannot be copied, only transferred.
• ✅ When a unique_ptr is out of scope, it automatically removes the object.

Unique_ptr Example in C++

Let us take an example to illustrate the Unique_ptr example in C++.

Example

#include <iostream>  

#include <memory>  

using namespace std;    //using standard namespace

    class Rectangle { 

    

    int length; // length of rectangle   

    int breadth; // breadth of rectangle   

  public:  

    Rectangle(int l, int b)  

    { // parameterised constructor  

        length = l;  

        breadth = b;  

    }  

     int area()  

    { // calculate area  

        return length * breadth; // return the area   

    }  

};  

  int main()    //main function

{  

    unique_ptr<Rectangle> P1(new Rectangle(20, 5));  

    cout << P1->area() << endl; // This print 100  

    // unique_ptr<Rectangle> P2(P1);  

    unique_ptr<Rectangle> P2;  

    P2 = move(P1);  

    

   cout << P2->area() << endl;    

    return 0;  

}

Output:

100

100

Explanation:

In this example, we demonstrate how unique_ptr manages dynamic memory for a Rectangle object. The ownership of the pointer is transferred from P1 to P2 using the move function, which ensures that only one unique pointer owns the object at a time. After that, the area is accessed using the arrow operator.

Shared_ptr

In the sharedptr, we can point more than one object to a single pointer at the same instance of time. A reference counter is maintained to denote the object using the usecount method.

Syntax:

It has the following syntax:

std::shared_ptr<Type> ptr = std::make_shared<Type>(args...);

Features of the shared_ptr function in C++

Several features of the shared_ptr function in C++ are as follows:

• ✅ It allows a shared ownership of a resource.
• ✅ It uses reference count internally.
• ✅ When the last shared_ptr is destroyed, the memory is removed.

Shared_ptr Example in C++

Let us take an example to illustrate the shared_ptr in C++.

Example

#include <iostream>  

#include <memory>  

using namespace std;  //using standard namespace

class Rectangle {

    int length;

    int breadth;

public:

    Rectangle(int l, int b) {

        length = l;

        breadth = b;

    }

    int area() {

        return length * breadth;

    }

};

int main() {   //main function

    shared_ptr<Rectangle> P1(new Rectangle(20, 5));  // Create shared_ptr P1

    cout << P1->area() << endl;

    shared_ptr<Rectangle> P2;  // Create shared_ptr P2

    P2 = P1;  // Now both P1 and P2 point to the same object

    cout << P2->area() << endl;

    // Both P1 and P2 are valid shared_ptrs to the same Rectangle

    cout << P1->area() << endl;

    // Reference count (use_count) will be 2

    cout << P1.use_count() << endl;

    return 0;

}

Output:

100

100

100

2

Explanation:

In this example, we demonstrate the sharedptr in C++. First, we have taken two smarcpp tutorialers (P1 and P2) that share ownership of a Rectangle object. After that, both pointers can access the area method, and usecount method that shows how many pointers are managing the object.

Weak_ptr

The weakptr is similar to the shared pointer. The main difference between weak and sharedptr is that it does not maintain a reference counter, and there is no stronghold of the object on the pointer. This property may result in a deadlock because different objects will try to hold the pointer.

Syntax

It has the following syntax:

std::weak_ptr<Type> wp = sp;

Features of weak_ptr in C++

Several features of the weak_ptr in C++ are as follows:

• ✅ Non-owner reference to a common shared resource.
• ✅ It is used to break the circular references that can occur when one and multiple shared_ptr instances reference each other, which helps to prevent memory leaks.
• ✅ It does not affect the reference count.

Weak_ptr Example in C++

Let us take an example to illustrate the weak_ptr in C++.

Example

#include <iostream>

#include <memory>

using namespace std;  //using standard namespace

class Child;

class Parent {

public:

    shared_ptr<Child> child;

    ~Parent() {

      cout << "Parent destroyed\n";

    }

};

class Child {

public:

    weak_ptr<Parent> parent;  // Weak reference to avoid circular dependency

    ~Child() {

        cout << "Child destroyed\n";

    }

};

int main() {   //main function

    {

        shared_ptr<Parent> p = make_shared<Parent>();

        shared_ptr<Child> c = make_shared<Child>();

        p->child = c;

        c->parent = p; // Only weak_ptr here avoids memory leak

        cout << "Parent use count: " << p.use_count() << endl;

        cout << "Child use count: " << c.use_count() << endl;

    }

    cout << "End of scope reached.\n";

    return 0;

}

Output:

Parent use count: 1

Child use count: 1

Child destroyed

Parent destroyed

End of scope reached.

Explanation:

In this example, we demonstrate the weakptr that avoids circular references. Here, the Parent class holds a sharedptr to the Child class, while the Child class holds a weakptr to the Parent class. It ensures that when both classes go out of scope, their destructors are called properly, which prevents memory leaks that are caused by cyclic sharedptr dependencies.

Differences between Raw pointers and Smarcpp tutorialers in C++

Several differences between Raw pointers and smarcpp tutorialers in C++ are as follows:

Conclusion

In conclusion, C++ smarcpp tutorialers automatically simplify memory management by handling resource allocation. They help to eliminate issues, such as memory leaks, dangling pointers, and manual delete calls. Smarcpp tutorialers, such as std::uniqueptr, std::sharedptr, and std::weak_ptr, each serve separate ownership requirements. These pointers support RAII, prompting safe and more maintainable code. Smarcpp tutorialers are necessary in modern C++ for clean and efficient memory use. Adopting them leads to stronger and error-free applications.

Smart Pointers MCQs

1) What happens if we try to copy a std::unique_ptr in C++?

• ✅ The program compiles and works as expected
• ✅ The object has been duplicated
• ✅ A compilation-time error occurs
• ✅ A runtime exception is thrown

2) What is the main advantage of using smarcpp tutorialers over raw pointers in C++?

• ✅ They increase the size of the program
• ✅ They help prevent memory leaks
• ✅ They require manual memory management
• ✅ They slow down the code

3) Why is std::unique_ptr preferred for single ownership of a resource in C++?

• ✅ It ensures special ownership and automatic deletion
• ✅ It supports copying
• ✅ It allows shared access
• ✅ It turns off dynamic memory

4) How does std::shared_ptr manage the lifetime of a resource in C++?

• ✅ It immediately removes resources
• ✅ It uses manual deletion
• ✅ It removes resources when the final shared_ptr is destroyed
• ✅ It never removes resources

5) What happens when a uniqueptr is moved to another uniqueptr?

• ✅ Both point to the same resource
• ✅ The original pointer is copied
• ✅ nothing happens
• ✅ Ownership is transferred; the original becomes null