Use of Private Constructor in C#

Question

Why we use Private constructor? How to access the method of Private constructor in C#?

Rajeev Kumar · Answer

Private constructors are used to prevent creating instances of a class when there are no instance fields or methods, such as the Math class, or when a method is called to obtain an instance of a class. If all the methods in the class are static, consider making the complete class static. Sealed class cannot be inherited but it can be instantiated. On the other hand, a class having a private constructor neither can be inherited nor instantiated due to its protection level

Kunal Vaishya · Answer

Simply to restrict to create the object of Class

Sandeep Singh Shekhawat · Answer

Private construtor is used to avoid default instance/object of class by application. It always forced to developer to create a parameterise construtor in that case we can initilization properties of that class and no need to extra setter for property. Private constructor uses when application is using single instance in single session of application means when an user is using an application and want operation from that class which have private constructor multiple times so in all time we will use single instance of that class to perform all operation which are realted to that object. It defines creational pattern means Singlton pattern for development of application. For More detail please go through following links: http://www.c-sharpcorner.com/UploadFile/SukeshMarla/learn-design-pattern-singleton-pattern/ http://www.c-sharpcorner.com/UploadFile/amit.dhania/singleton-pattern/ http://www.c-sharpcorner.com/UploadFile/ff2f08/singleton-design-pattern/ http://www.c-sharpcorner.com/UploadFile/4d790c/singleton-pattern-creational-pattern/ http://www.c-sharpcorner.com/UploadFile/40e97e/singleton-pattern/ http://www.c-sharpcorner.com/uploadfile/ashish_2008/singleton-design-pattern-in-C-Sharp/ Thanks Sandeep

Santhosh Kumar Jayaraman · Answer

The private constructor ensures that it is impossible for the class to be instantiated directly from external classes. When you want to prevent the users of your class from instantiating the class directly. Some common cases are: Classes containing only static methods Singletons Factory Design patterns most common example is singleton pattern using System; public sealed class Test { public static readonly Test Instance = new Test(); // Singleton pattern public int A; // Instance field private Test() // This is the private constructor { this.A = 5; } } class Program { static void Main() { // We can access an instance of this object that was created. // ... The private constructor was used. Test test = Test.Instance; // These statements show that the class is usable. Console.WriteLine(test.A); test.A++; Console.WriteLine(test.A); } } Output 5 6 Check this http://www.dotnetperls.com/private-constructor