var i; how many values return?

Vulpes gave you the answer. It's not valid in C#. var i =new List() means i is a type of List and var i=new Person() means it is a type of Person.

hi,

Var keyword define type of variable implicit. An implicitly typed local variable is strongly typed just as if you had declared the type yourself, but the compiler determines the type

Please refer
http://msdn.microsoft.com/en-us/library/bb383973.aspx
http://www.dotnetperls.com/var

Agree with Vulpes

Var I; does not return anything but it gives compilation error....

hope this will help you.

I'm not surprised that it confused you since:

var i;

doesn't return any values at all. It's simply a variable declaration.

Moreover, it's not even valid C# syntax except in the very unusual circumstance that you have a class or struct called 'var' in scope within your application. In that case, it declares 'i' to be a variable of the 'var' type.

The much more usual use of 'var' is to declare a local variable's type implicitly. The compiler infers the type of the variable by working out the type of the expression on the right hand side of the '=' sign. For example:

var i = 3; // 'i' inferred to be of type int
var j = true; // 'j' inferred to be of type bool
var k = new MyType(); // 'k' inferred to be of type MyType

Clearly, some expression needs to be assigned to the variable for the compiler to be able to infer the type.

Notice that the variable is still 'strongly' typed i.e. you can't then assign an expression of a different type to it. For example this is illegal:

i = 2.5; // illegal, 'i' is of type int not double.