std::make_unique in C++ 14

std::make_unique is a utility function in C++ that was introduced in C++14. It is used to create a unique_ptr object, which is a smart pointer that manages the lifetime of dynamically allocated objects. It is defined inside <memory> header file.

Syntax

std::make_unique <object_type> (arguments);

Parameters

• object_type: It is the type of object you want to create.
• arguments: It is the argument list for the constructor of object_type.

Return Type

• This function returns a unique_ptr of type object_type.

It is the preferred way to create a std::unique_ptr, as it is safer than using the new operator directly because the object is automatically destroyed when it goes out of scope.

Examples of std::make_unique

The following programs demonstrate how to implement std::make_unique() in our programs.

Example 1

// C++ code to implement std::make_unique()
#include <iostream>
#include <memory>
using namespace std;

class Geeks {
public:
    Geeks() { cout << "Object Created\n"; }  // constructor
    ~Geeks() { cout << "Object Destroyed"; }  // destructor
};

void f()
{
      // creating unique ptr object
    unique_ptr<Geeks> o = make_unique<Geeks>();
}

int main()
{

    f();
    return 0;
}

Object Created
Object Destroyed

Example 2

// C++ code to implement std::make_unique()
#include <iostream>
#include <memory>
using namespace std;

class Geeks {
public:
    int d;

    // construtor
    Geeks(int x)
    {
        this->d = x;
        cout << "Object Created\n";
    }

    // destructor
    ~Geeks() { cout << "Object Destroyed"; }
};

void f()
{
    // creating unique ptr object
    unique_ptr<Geeks> o = make_unique<Geeks>(10);
    cout << o->d << endl;
}

int main()
{

    f();
    return 0;
}

Object Created
10
Object Destroyed

Advantages of std::make_unique

• Unlike new, make_unique is exception safe.
• No cleanup is necessary if make_unique is not evaluated.