---
title: "What is the C++ Singleton design pattern?"  
description: "What is the C++ Singleton design pattern?"  
author: "Utpal Vishwas"  
published: 2023-07-07  
updated: 2023-07-10  
canonical: https://www.mindstick.com/forum/158999/what-is-the-c-plus-plus-singleton-design-pattern  
category: "visual c++"  
tags: ["c++", "programming language"]  
reading_time: 2 minutes  

---

# What is the C++ Singleton design pattern?

What is the [C++](https://www.mindstick.com/blog/745/array-in-c-plus-plus) [Singleton design](https://www.mindstick.com/forum/33927/how-to-implement-singleton-design-pattern-in-c-sharp) [pattern](https://www.mindstick.com/forum/2314/what-is-the-mvp-and-mvc-pattern)?

## Replies

### Reply by Aryan Kumar

The [Singleton](https://www.mindstick.com/blog/10912/java-singleton-pattern) [design](https://www.mindstick.com/articles/12279/interior-design-and-furniture-store-wordpress-theme) pattern in C++ ensures that only one instance of a class is ever created. This can be useful for classes that need to maintain global state, such as a logger or a configuration object.

To implement the Singleton pattern in C++, you can use the following steps:

1. Make the class constructor private. This will prevent other classes from directly creating instances of the class.
2. Create a private static member variable of the class that will hold the instance of the class.
3. Create a public static method that returns the instance of the class. This method should check to see if the instance has already been created. If it has, the method should return the existing instance. If it has not, the method should create a new instance and return it.

Here is an example of how to implement the Singleton pattern in C++:

C++

```plaintext
class Singleton {
 private:
  Singleton() {}
  static Singleton* instance;

 public:
  static Singleton* getInstance() {
    if (instance == nullptr) {
      instance = new Singleton();
    }
    return instance;
  }
};

Singleton* Singleton::instance = nullptr;
```

The `Singleton` class has a private constructor, which means that other classes cannot directly create instances of the class. The class also has a private static member variable called `instance`. This variable will hold the instance of the class.

The `getInstance()` method is a public static method that returns the instance of the class. This method first checks to see if the `instance` variable has already been initialized. If it has, the method simply returns the existing instance. If it has not, the method creates a new instance of the class and stores it in the `instance` variable. The method then returns the `instance` variable.

This is just one way to implement the Singleton pattern in C++. There are other ways to implement the pattern, and the best way to implement it will depend on the specific needs of your application.


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Original Source: https://www.mindstick.com/forum/158999/what-is-the-c-plus-plus-singleton-design-pattern

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