Question

I have a static public List of type BoxPair which I’m trying to write stuff to, but it changes every record every time I add a new entry into it. I’m hoping someone can see what’s going wrong here, as it’s driving me slightly insane. The full addition code is below:

public static List<BoxPair> CreateBoxPair (int iBoxCount)
{
    SetTopBox primary;
    SetTopBox backup;

    for (int i = 0; i < iBoxCount; i++)
    {
        primary = new SetTopBox();
        backup = new SetTopBox();

        primary.IBoxNumber = i;             
        primary.SDeviceName = "Box" + (i + 1).ToString("00");
        primary.Role = Box.ROLE_PRIMARY;

        backup.IBoxNumber = i;
        backup.SDeviceName = "Box" + (i + 1).ToString("00");
        backup.Role = Role.ROLE_BACKUP;

        lstBoxes.Add(new BoxPair(primary, Role));
        lstBoxes.Add(new BoxPair(backup, Role));

        foreach (BoxPair p in lstBoxes)
        {
            Declarations.BOXES.Add(p);
        }             
    }                        

    return lstBoxes;
}

I know it’s going to be something basic, but from what I can see, I’m always using a new primary/backup box, so nothing should conflict. Any ideas would be greatly appreciated.

Cheers.

P.S. Every post I make, SO removes the first word, so I have to type it twice. Any ideas as to why that happens?

EDIT: As all the approaches listed below have given the same result, I’m guessing that this is a problem that cannot be solved. Therefore, I’m returning to the drawing board to try and approach this differently. Thanks for all the help, anyways, chaps 🙂

Answer 1

From the comments my best bet on code that works is as follows:

public static List<BoxPair> CreateBoxPair (int iBoxCount)
{
    for (int i = 0; i < iBoxCount; i++)
    {
        var primary = new SetTopBox();
        var backup = new SetTopBox();

        primary.IBoxNumber = i;             
        primary.SDeviceName = "Box" + (i + 1).ToString("00");
        primary.Role = Box.ROLE_PRIMARY;

        backup.IBoxNumber = i;
        backup.SDeviceName = "Box" + (i + 1).ToString("00");
        backup.Role = Role.ROLE_BACKUP;

        var primaryPair = new BoxPair(primary, Role);
        var backupPair = new BoxPair(backup, Role);

        lstBoxes.Add(primaryPair);
        lstBoxes.Add(backupPair);

        Declarations.BOXES.Add(primaryPair);
        Declarations.BOXES.Add(backupPair);
    }                        

    return lstBoxes;
}

I think there are two issues in the original code:

• primary and backup being declared outside the loop.
• The foreach loop inside the loop adding the entries to the other collection multiple times.