improve the exception handling vb.net

Question

I have a small trouble with the performance of the exception handling. I\'m building... aaaaa... soooo...hmmm...a graph db? yeah something like this... with vb.net. I\'m buildi

Answer 1

You are using Exceptions to fix a problem when your code encounter a value that cannot be converted to a double. This is called driving your code using exceptions and it is a bad practice. Catching exceptions is never a good fix for this scenario.

In particular when there is a clear way to avoid them

 For i As Integer = 0 To pR.r.wsRowCount - 1
     Dim d1 As Double
     Dim d2 As Double

     if Double.TryParse(pR.r.wsItem(ca.ix, i), d1) Then
        if Double.TryParse(pR.r.wsItem(cb.ix, i), d2 Then
             pR.r.wsItem(cix, i) = (d1 * d2).ToString()
        else
             pR.r.wsItem(cix, i) = String.Empty
        End If
     Else
        pR.r.wsItem(cix, i) = String.Empty
     End If
 Next

Convert.ToDouble cannot handle the fact that a string is not a valid numeric value and if it encounter this case it throws an exception. Throwing an exception is costly in terms of perfomance in particular for gathering the information about the call stack.

Instead, if there is the possibility that your input contains values that cannot be converted to double, then Double.TryParse is the correct way to proceed also if your benchmarks show a little difference in performance. Double.TryParse doesn't raise an exception if the string passed cannot be converted to a double, but return false. In this way the costly exception is avoided and you have a more predictable time of execution

Said that, you should really reevaluate your approach to store every kind of data in some string structure. The need of constant conversion between a string and the intended data type could be a real bottleneck here.