C#7: Underscore ( _ ) & Star ( * ) in Out variable

Question

I was reading about new out variable features in C#7 here. I have two questions:

1. It says

   We allow \"discards\" as out parameters as w

Answer 1

Q: ... we can do so in pre C#7.0 too:

var _;
if (Int.TryParse(str, out _))

or am I missing something here?

That isn't the same thing.
Your code is making an assignment.

In C# 7.0 _ is not a variable, it tells the compiler to discard the value
(unless you have declared _ as a variable... if you do that the variable is used instead of the discard symbol)

Example: you can use _ as a sting and an int in the same line of code:

string a; 
int b;
Test(out a, out b);
Test(out _, out _);

//...

void Test(out string a, out int b)
{
   //...
}