Error Handling in C# with Exceptions

Question 1

Why handling errors? list 4 reasons

Answer 1

• So the program doesnt crash.
• Gives the chance to fix/retry.
• meaningful message and graceful exit
• opportunity to log erros

Question 2

Why using exceptions instead of error codes?

Answer 2

more readable , exceptions can bubble up, can catch excptions at higher levels or sigle place… handle system errors… better documentable in the constructors.

Question 3

What an exception is made of?

Answer 3

Is an object that inherits from system.Exception and is created via throw statement.

Question 4

What is an exception?

Answer 4

any error condition or unexpected behavior that is encountered by an executing program.

Question 5

how exceptions are organized?

Answer 5

via an hierarchy of classes.

see here: https://pasteboard.co/JCvqsHk.png

Question 6

What are the properties exposed by an exception class?

Answer 6

Message: the explataion of what happened.
Stack trace: all the call chain.
Data: key value pair with extra data.
InnerException: Exception that caused the exception.
Source: application/object name that caused the error (assembly).
Help link: help information about the error;
Target site: method that threw the exception plus a lot of good information reflected.

Question 7

What are the guidelines of an ApplicationException and SystemException class?

Answer 7

should not be thrown, extended or caught (unless you plan rethrowing it)

Question 8

What should i do when I want to catch an OutOfMemoryException?

Answer 8

call Environment.FailFast to terminate the app and log to the console

Question 9

What happens when an exception is not handled by the application or framework?

Answer 9

the app will crash (stopped working).

Question 10

How to create try catch block that treats different exception types? Does the order matter?

Answer 10

multiple catches are defined… the order is from most specific to least specific. top down

Question 11

What are some exception handling good practices?

Answer 11

• catch blocks that swallow exceptions;
• invalid inputs, for eg, is not and exceptional situation.. you need to validate (or code to handle that).
• Design code to avoid exceptions.
• Localize error messages (the exceptions itself).
• use finally for cleanups.