Your own exception hierarchy in C#
C# interview exercise on Exceptions & Disposal, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Give the three exception types their base classes and messages: ConfigException derives from Exception; MissingKeyException(key) and InvalidValueException(key, value) derive from ConfigException, with the messages "missing key: port" and "invalid value for port: 'abc'". Then write GetPort(config): the "port" entry as an int between 1 and 65535. Callers can catch ConfigException to handle both.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.