How to Create a shared_ptr in C++?

A std::shared_pointer is a smart pointer introduced in C++11 that manages the lifetime of a dynamically allocated object through reference counting. In this article, we will learn how to create a shared_pointer.

shared_ptr in C++

A std::shared_pointer can be created by using the std::make_shared method which is defined in <memory> header in C++. Use the below syntax to create a shared_ptr.

Syntax to Create shared_ptr in C++

auto sharedPtr = make_shared<Type>(constructor_arguments);

Here,

• Type is the type of the object that we want to allocate and manage with the std::shared_ptr.
• constructor_arguments are the arguments that are passed to the constructor of Type.

C++ Program to Create shared_ptr

The below demonstrates how we can create a shared_ptr using the make_shared function and then access a member function of the class.

C++

// C++ program to create shared_ptr
#include <iostream>
#include <memory>
using namespace std;

// defining my class
class MyClass {
public:
    // constructor of myClass
    MyClass() { cout << "MyClass Constructor\n"; }

    // destructor of myClass
    ~MyClass() { cout << "MyClass Destructor\n"; }
    void printHello() const { cout << "Hello!" << endl; }
};

int main()
{

    // Creating a shared_ptr using make_shared
    shared_ptr<MyClass> mySharedPtr
        = make_shared<MyClass>();

    // Use the shared_ptr
    mySharedPtr->printHello();

    // The MyClass instance will be automatically destroyed
    // when  mySharedPtr goes out of scope

    return 0;
}

Output

MyClass Constructor
Hello!
MyClass Destructor

Note: We can also create shared_ptr by directly using std::shared_ptr constructor.