[RESOLVED] Doesn't return value on all code paths

[graham23s]

Hi There Guys,

I'm trying to get my head around this issue, on a few of my functions i get a warning " 'functionDealWithHiddenFields' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used."

Example function:

Function functionDealWithHiddenFields(ByVal HTML As String, ByVal numHiddenFields As Integer, ByVal X As Integer)
 
        Try
 
            'For i As Integer = 0 To numHiddenFields
            '// The html source
            Dim sText = HTML
 
            '// The string we are searching for
            Dim sPattern As String = "(?<=<input type=""hidden"" class="").*?(?="".*?')"
 
            '// This is the regular expression
            Dim regex As New Regex(sPattern, RegexOptions.IgnoreCase Or RegexOptions.Singleline)
 
            '// The matches that we return are put in the matchcollection
            Dim regexMatches As MatchCollection = regex.Matches(sText)
 
            '// Return
            'Return regexMatches(0).ToString
            'MessageBox.Show("Hidden Field " & X & ": " & regexMatches(X).ToString)
 
            Return regexMatches(X).ToString
 
        Catch ex As Exception
 
            MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
 
        End Try
 
    End Function

The functions still work correctly (as far as i can tell) what would i need to do to the above function to remedy that warning?

thanks for any info guys

Graham

[keystone_paul]

Its basically saying if you fall into the "Catch" block then your function doesn't return anything.

You don't need to fix it but if you don't want that message occurring all the time just put a line within the Catch block to return something (whatever is appropriate)

[techgnome]

You have a Return in the Try portion of the block.... but not in your Catch... so if an exception does happen, the funtion will return a NULL (or Nothing) ... which could cause problems for the code that calls that function.

-tg

[jmcilhinney]

The cause has already been established. The pattern you have is this:

Try
    'Do something.
 
    Return someValue
Catch
 
End Try

To solve the issue you could do this:

Try
    'Do something.
 
    Return someValue
Catch
    Return Nothing
End Try

but, in many people's eyes, including mine, it is more correct to do this:

Dim result = Nothing
 
Try
    'Do something.
 
    result = someValue
Catch
  
End Try
 
Return result

Having a single point at which your method always ends is considered good practice by many as it tends to be clearer.

[graham23s]

Hi Thank you for the input, that has definately cleared things up

then check if (function is not nothing) to see if we got avalue returned would that be right?

thanks guys

Graham

[Pradeep1210]

Hi Thank you for the input, that has definately cleared things up

then check if (function is not nothing) to see if we got avalue returned would that be right?

thanks guys

Graham

Yes that's right.

I personally like jm's 3rd way in the sense that it is more logical to human understanding. When you just declare an object, it is nothing. After whatever processing you do you just return that object, whether it has or doesn't have anything. You don't need to deal with all those individual cases; really helpful in complex cases where there are multiple code paths.

[graham23s]

Thanks a lot guys, as a rule of thumb i will do it like that in future

thanks again

Graham