Question

Possible Duplicate:
C# ‘var’ vs specific type performance

When I write below code:

List<string> list = new List<string>();  

resharper wants to convert it to

var list = new List<string>();          

Why? What is the difference?
Is it more understandable? I think not.

Using var has more than the other cost on RAM. Isn’t it?

Answer 1

They are the same. var is implicitly typed.

If you hover over the keyword var in Visual Studio, it will show you the type of your object – in this case List<string>. The use of var is only to clean up code – you already know you’re creating an object of type List<string>, so some people think it is redundant to type:

List<string> list = new List<string>();

There is no performance difference, as the compiler already knows what type the object is. Using var personal preference mostly – you can use it if you want to and there is no performance hit.

Eric Lippert has a great blog post about var here.

I think you’re confusing var and dynamic, which are two totally different things. The dynamic type is a type that allows you to assign values of different types to it at runtime.