Using var or not using var [duplicate]

Question

Possible Duplicate:
C# 'var' vs specific type performance

Hi all,
I recently saw code that uses var a lot.
E.g.:

var myString = GetAnyString();
var myInstance = GetClass();

instead of

string myString = GetAnyString();
MyClass myInstance = GetClass();

Besides the readability (I think that using var is not very readable), are there any advantages and/or drawbacks using it? How about performance

Answer 1

It is subjective, but I don't like using vars. As for me they don't improve readability.

But general guideline on var usage is following:

Use var when it is absolutely clear what type of the variable is being declared:

Dictionary<string, Dictionary<string, string>> varOfSomeLongType = new Dictionary<string, Dictionary<string, string>>();

or when you are declaring variable of anonymous type:

var linqResult = from element in SomeCollection
                 select new { element.A, element.B }