Why does ReSharper recommend using the keyword "as" instead of "is"?

Question

I use Resharper8 and when I wrote

if (sender is Button) 

Resharperreturn the use of the keyword asand change it to:

Button button = sender as Button;
if (button != null)

Is there any special reason?

use aswhat is better than is? or is it asbetter in this case ?

Answer 1

asperhaps better if the resulting expression is used later; isjust as good if not. For instance.

if (sender is Button) {
    Button button = (Button)sender;  // just use `as`, as suggested
    button.Push();

(I thought ReSharper only gave a warning / hint in the case where the duplicate can be deleted, for example this.)

In doing so, I use the structure

Button button;
if ((button = sender as Button) != null) {
    button.Push();

, ( ) - as #/ReSharper [] .

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Answer 2

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Answer 3

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Answer 4

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