What is meant by error handling support in dot net?

Answer 1

The idiomatic way to express error conditions in .NET framework is by throwing exceptions. In C#, we can handle them using the try-catch-finally statement:

try

{

// code which can throw exceptions

}

catch

{

// code executed only if exception was thrown

}

finally

{

// code executed whether an exception was thrown or not

}

Whenever an exception is thrown inside the try block, the execution continues in the catch block. The finallyblock executes after the try block has successfully completed. It also executes when exiting the catch block, either successfully or with an exception.

In the catch block, we usually need information about the exception we are handling. To grab it, we use the following syntax:

catch (Exception e)

{

// code can access exception details in variable e

}

The type used (Exception in our case), specifies which exceptions will be caught by the catch block (all in our case, as Exception is the base type of all exceptions).

Any exceptions that are not of the given type or its descendants, will fall through.

We can even add multiple catch blocks to a single try block. In this case, the exception will be caught by the first catch block with matching exception type:

catch (FileNotFoundException e)

{

// code will only handle FileNotFoundException

}

catch (Exception e)

{

// code will handle all the other exceptions

}

This allows us to handle different types of exceptions in different ways. We can recover from expected exceptions in a very specific way, for example:

• If a user selected a non-existing or invalid file, we can allow him to select a different file or cancel the action.
• If a network operation timed out, we can retry it or invite the user to check his network connectivity.

For remaining unexpected exceptions, e.g. a NullReferenceExceptions caused by a bug in the code, we can show the user a generic error message, giving him an option to report the error, or log the error automatically without user intervention.