Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What does the "is" operator do in C#?

1. Checks if an object is of a compatible type

2. Converts an object to a specified type

3. Creates a new instance of an object

4. Returns the hash code of an object

The correct answer is: Checks if an object is of a compatible type

The "is" operator in C# is specifically designed to check whether an object is of a compatible type. This operator confirms whether the runtime type of the object matches the type specified. When you use "is," you can safely ascertain if an object can be treated as a certain type without causing an InvalidCastException. This is particularly useful in situations involving polymorphism or when working with collections of base types, allowing developers to write safer and more robust code. For example, if you have an object of a base class and want to check if it is derived from a specific subclass, using the "is" operator allows you to perform that check easily and concisely. The other options pertain to different functionalities in C#. For instance, converting an object to a specified type relates to the "as" operator or direct casting; creating a new instance of an object typically involves using the "new" keyword; and returning the hash code of an object refers to the GetHashCode() method in the Object class. Each of these concepts serves distinct purposes within the language, further illustrating the unique functionality of the "is" operator in type checking.