C++ Programming - OOPS Concepts - Discussion

A Singleton class is a design pattern, which creates only a single instance at any time.

When is it required:

Based on the requirement.

Example : Singletons are often used to control access to resources such as database connections or sockets.

Suppose u have licence for only one connection for database, A singleton connection obj makes sure that only one connection can be made at any time.

How this can be implemented:

1. Have a static method, creates the instance if the instance does not exists. If the instance already there then returns the reference to the existing obj.

2. Have a private constructor.

Why Static method:

No obj is required to call static method and memory is used only when required.

private constructor is to make sure that object is not created in any other way.

I explained as per my knowledge. Hope this would be useful.

When class having only one class is called singleton class;

Means that single=means one it means that required of one object.

So the class derived as private is called singleton class?

How we create singleton class?

What is meant by singleton class?

How to make singleton class?

Making constructor as private it will not allow any other function even main to create an object. Only inside class, object can be created.

Singleton means only one instance or object at a time can be created.

Why using (for eg: only one person can open a mailbox from a system using a web browser from a system).

What is use of this mainly in c++?

I expect that friend, virtual class doesn't access more than one object.