Private and Public variables in C#

Question

Sir I need your help in the following:- I declare a member variable as private. Then provide access to them with public modifier what is the benefit of declaring a member variable as private? could you give me a example?

Vulpes · Answer

Declaring class level variables (or 'fields') as public is generally frowned upon by experienced developers. It is considered better to declare the field to be private and then controlling access to it using a public property. That way you can make sure that the user doesn't assign an invalid value to it. For example: class Person { int _age; public int Age { get { return _age; } set { if (value 125) throw new ArgumentException (Age must be be between 0 and 125); else _age = value; } } } Even when the argument is not checked for correctness it's still considered better to use properties in case checking is introduced at a later stage. If you have to change from a field to a property this changes the public interface of your class. At one time this used to be quite tedious and lead to code bloat but since the introduction of automatic properties it's no longer a problem: public string Name { get; set; }

Vulpes · Answer

Well I'm sure you can appreciate the main point which is that you can prevent a field being assigned an invalid value if you use a public property and a private field. You simply can't do that with a public field. You can assign it any value which the field's type can accomodate whether it's a sensible value or not. Now in some cases you don't actually care what value a field is given and so you might say why not simply use a public field in those cases? The trouble is that if you do this and then later decide that you do care what values the field is given after all then if you change from a public field to a public property this alters the interface of your class. If other code is using your class then it will need to be recompiled which would not be necessary if you'd used a property from the start. Of course if your class is not being used by other code you could argue that using a property bloats your code and this is true. However since automatic properties came along this is no longer much of a concern. You can just stick {get; set;} on the end of a public field declaration and hey presto it's now a property! So there's no longer much of an excuse for avoiding public fields and always using properties instead.

shilpaka anjinappa · Answer

Public :- if you want any variabel or access values through to other class with int he project we can delcare as public. else private memeber is fine. if you want to access variable with other class as well made it as internal

Santosh Yadav · Answer

Thanks a lot sir.

Santosh Yadav · Answer

It means that there is no much difference between public variable of a class and properties ? Still not clear sir. Please help.

Kailash Chandra Behera · Answer

private variable is only access to the class where the variable exist. it can not be accessed out side of the class. for example: if your create the object of that class in which private variable is exist. the private variable will not be access to that object