The is pattern expression extends the familiar is operator to query an object beyond its type.
Try the following code:
Change the variable declaration to a string instead:
object count = "5";Now, the is expression is false, so the else branch is executed. Try to change count to number in the else branch:
Console.WriteLine($"{number} is not an integer");That change won't compile because number isn't assigned in the else branch. It's only assigned in the true branch of the if statement.
In addition to the type pattern, you can use the constant pattern with the is statement. Add the following lines before the first if statement:
if (count is 0)
Console.WriteLine("count is zero");Modify the declaration of count to try different values.
The is expression type pattern is useful when you have a small number of types to test against. Often, you may need to test multiple types. That requires the pattern matching switch statement.