Using interfaces when you aren’t going to have multiple implementations of it is an example of interface overuse. Creating an interface for a class that matches the public members of the class ...

Until C# 8.0, an interface in C# could not contain method definitions. You could only include method declarations in an interface, and the members of an interface were public and abstract by default.

Checking If You Can Use a Class in C# The is keyword lets you check if a variable is pointing to an object of a particular class (or a class that inherits from some class). For example, the code in ...