CODEWITHSUNDEEP
c#vb.netwinforms
Apoorv
Apoorv

Reputation: 2043

C# alternative to the VB code

I have this VB code 

Try
    For i = 0 To OutData.NumMerids - 1
        With OutData.MeridData(0)
            .NumCurves = InStepFiveData.ConvexSurfaceData.MultiCurveData.NumOzCurves + InStepFiveData.ConvexSurfaceData.MultiCurveData.NumLenticularCurves
            ReDim .CurveData(.NumCurves - 1)
        End With
    Next
    ...

I want to generate similar C# code. I used some logic and deducted the code below. 

try
{
    for (i = 0; i <= OutData.NumMerids - 1; i++)
    {
        //   var _with25 = OutData.MeridData[0];
        OutData.MeridData[0].NumCurves =(short) (InStepFiveData.ConvexSurfaceData.MultiCurveData.NumOzCurves + InStepFiveData.ConvexSurfaceData.MultiCurveData.NumLenticularCurves);
        // ERROR: Not supported in C#: ReDimStatement
        Array.Resize(ref OutData.MeridData[0].CurveData, OutData.MeridData[0].NumCurves - 1);
    }
    ...
}

Just want to know that am I doing something wrong ?

Thanks

Upvotes: 4

Views: 188

Answers (3)

JamesFaix
JamesFaix

Reputation: 8665

A few things you can correct/improve:

C# for loops require you to declare the loop variable.

for(var i = 0; i < 100; i++) {

This might not be an issue if you've already declared i somewhere above, but I would recommend keeping the iterator variable limited to the scope of the loop if possible.

As a substitution for VB's With I would use a local variable. (I believe this is what With actual does behind the scenes.) It looks like you commented that out for some reason. Every time you reference OutData.MeridData[0] or InStepFiveData.ConvexSurfaceData.MultiCurveData you have to deference several objects, and depending on the structure ofthose objects that could be inefficient. Plus it's hard to read.

@Dave Doknjas got the Redim substitution part right, you just need to use a constructor. Redim actually throws out the old array and creates a new one, so its name is actually a bit misleading. To Redim Preserve you would need to use Array.Copy to move values from the old array to the new one.

try {
   for (var i = 0; i <= OutData.NumMerids - 1; i++) {
      var meridData = OutData.MeridData[0];
      var curveData = InStepFiveData.ConvexSurfaceData.MultiCurveData;
      meridData.NumCurves = (short)(curveData.NumOzCurves + curveData.NumLenticularCurves);
      meridData.CurveData = new Foo[meridData.NumCurves];
   }
}

Upvotes: 1

Sehnsucht
Sehnsucht

Reputation: 5049

The error lies in the Array.Resize statement ; more specifically in the size given.

In VB.Net you give the last index of the array where in C# you give the length of the array
So there is a shift of 1 between the two. 

ReDim .CurveData(.NumCurves - 1)
' equivalent to
ReDim .CurveData(0 To .NumCurves - 1) ' length is (.NumCurves - 1) - 0 + 1 = .NumCurves

This comes from the fact that in VB6 you could have an array indexed in other base than 0 (notably the 1 indexed collection) and so that was valid (it isn't in VB.Net)

Dim someArray(-4 To 5) As Integer ' declares an array of 10 integer indexed from -4 to 5

Back to your code you just need to give the size

//Array.Resize(ref OutData.MeridData[0].CurveData, OutData.MeridData[0].NumCurves - 1);
// replaced by
Array.Resize(ref OutData.MeridData[0].CurveData, OutData.MeridData[0].NumCurves);

As for the comment given by Ashwin Nair ; ReDim has the same behaviour (I wouldn't be surprise ReDim uses Array.Resize internally in .Net)

Edit :

As Dave said in it's answer Array.Resize is the translation of Redim Preserve not Redim (which wipes the data away)

Upvotes: 2

Dave Doknjas
Dave Doknjas

Reputation: 6542

You (and the accepted answer) are confusing 'ReDim' with 'ReDim Preserve'. Your 'ReDim' statement is just converted using a 'new' statement to create the array:

OutData.MeridData[0].CurveData = new Foo[OutData.MeridData[0].NumCurves];

(The type of 'CurveData' is unknown to me, so I used 'Foo' - you'll have to replace with the appropriate type).

Upvotes: 2

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