Why does c# need "var" identifier? [duplicate]

Question

Possible Duplicate:
What's the point of the var keyword?

Why does c# need the "var" identifier for type inferred type variables?

I mean what is the problem with just leaving it off:

a = 1;
//vs
var a = 1;

Reading Programming in Scala:

"Type variable" syntax you cannot simply leave off the type - there would be no marker to start the definition anymore.

But what is the different between leaving it off in the a:Int or int a?

Answer 1

At least one reason that comes to mind is that it forces the programmer to declare their intent to introduce a new variable, as opposed to assigning to an existing variable. This enables the compiler to detect numerous common coding errors.

Answer 2

Consider this:

class Foo
{
    int a;

    void Bar()
    {
        var a = 1;
    }
}

Without the var keyword, the assignment would be to the class member a.

var introduces unambiguously a new local variable.