Microsoft Certified Solutions Developer (MCSD) Certification Practice Test

What is the result of using the "as" operator in C#?

1. Returns a boolean indicating success

2. Returns a converted value or null if unsuccessful

3. Throws an exception if conversion fails

4. Prompts the user for input

The correct answer is: Returns a converted value or null if unsuccessful

The "as" operator in C# is used for type conversion and is particularly helpful when dealing with reference types. When you apply the "as" operator, it attempts to convert an object to a specified type. If the conversion is successful, it returns the converted value. However, if the conversion cannot be performed—meaning the object does not inherit from the specified type or is not compatible with it—the operator does not throw an exception; instead, it returns null. This characteristic makes the "as" operator a safe way to attempt type conversions without risking a runtime exception, allowing developers to handle conversion failures gracefully by checking for null. This behavior is distinctly different from other operators or methods that may throw exceptions upon failed conversions, like the explicit cast or methods such as Convert.ToInt32, which will generate exceptions if the conversion fails. Additionally, the "as" operator is not connected to user input or direct boolean success indicators, as its purpose is strictly type conversion without prompting for user interactions.