Change return type of a function on error?

Question

User2059472900 posted

Hi

if i got a function with a try cath block inside

and the function should return an integer.

how would i do it that the function can return me a the error message?

public function test() as Integer

try
  do something

  return integer

catch
 return errormessage   (as string)
end try


End Function

thx

greetings jamal

Answer 1

User-1181492241 posted

Hi, as your function is returing integer, you cannot return the error message. You can try something like this, (The syntax will be wrong)

public function test() as Integer
 try
  do something
  return integer
 catch
   throw
 end try
End Function

public function Main
 string errorMessage
 try
  Int x = test()
 catch (Exception ex)
     errorMessage = ex.Message
    throw
 end try
End Function 

Answer 2

User2059472900 posted

im not @ work so i cannot test it right now,

but i got 2 questions to your reply:

after "throw" do i have to write something?

and in the Main function, wont there just be an error that test has to be an int if i want to set it to X  ?

thx

greetings :)

Answer 3

User-1181492241 posted

throw in test() function - means rethrowing the exception so that you can catch the same exception in Main function.
And in main function you can get exception details and do some thing like show message to user or something...

public function Main
 string errorMessage
 try
  Int x = test()
 catch (Exception ex)
     errorMessage = ex.Message
     Response.Write("Error : Details - " + ex.Message)
 end try
End Function

Sorry, I didnt understand the second question.

 

Answer 4

User2059472900 posted

ok thanks im going to try it

Answer 5

User-952121411 posted

Technically a "Try-Catch-Throw" is pointless in the test() method.  It is a misconception that exceptions need to be rethrown. In fact it can hinder the process by messing up the callstack when trying to trace where the actual exception occured.

 

While technically still not incorrect, the "better" or preferred method is to let exceptions bubble up on their own as they will by default. If you can;t actually habdle the exception in the test() method and do something meaningful with it, then letting the exception bubble up to log at the topmost method will work. Take a look or test it out:

Public Sub MainCallingMethod()

  Try
     'Call the method that we know will throw an exception
     'and it will bubble up by default
     test()
  Catch(ex As Exception)
     Dim ExMessage As String = ex.Message.ToString()
  End Try

End Sub

Public Function test() As Integer

      Dim i As Integer = 1
      Dim j As Integer = 0

      'This line will divide by zero and throw an exception on purpose
      Dim Result As Integer = i / j

End Function

You could even do one thing better in the code above and actually test for a 'DivideByZero' exception type if you wanted rather than just type 'Exception'. However the point here is to show you how to allow exceptions no matter how many layers or levels down to bubble up and be caught at the layer that can actually do something meaningful (i.e. log it, display it, etc.)

Hope this helps!