Question

Im converting this simple program from vb to c# it updates, displays, create and delete items from a little access database. Bellow is the PopulateListBox() function in VB it goes through every row in the data set and see if it is deleted, not deleted or has errors. I am getting 2 errors here both on the lines
lstAlbums.Items.Add(item);
and
lstAlbums.Items.Add(delitem);
now i realise that the strings are unassigned so i added
string item = “”;
string delitem = “”;

then when i start the program it fills every second item in th list box with a blank row.

How do i overcome this situation? thank you in advance anyone how can help me.

    private void PopulateListBox()
    {
        string item;
        string delitem;
        //clear the list box
        lstAlbums.Items.Clear();

        //access each row in the data set table

        foreach (DataRow row in myDataSet.Tables["albums"].Rows)
        {
            //list the nondeleted rows
            if (!((row.RowState & DataRowState.Deleted) == DataRowState.Deleted))
                item = row["albumCode"] + ", " + row["AlbumTitle"] + ", " +                                row["ArtistCode"];
                    //list rows with update errors
                    if (row.HasErrors)
                    item = "(**" + row.RowError + "**)";
                lstAlbums.Items.Add(item);

            //list deleted rows
            if ((row.RowState & DataRowState.Deleted) == DataRowState.Deleted)
                delitem = row["albumCode", DataRowVersion.Original] + ", " 
                    + row["AlbumTitle", DataRowVersion.Original] + ", " 
                    + row["ArtistCode", DataRowVersion.Original] + "***DELETED***";
            lstAlbums.Items.Add(delitem);
         }

Answer 1

You’re missing the opening and closing braces { and } in your if statement, so the statement immediately following the if statement executes if the condition matches, and the statement after that always executes.

In VB.NET your if statement resembles this:

If condition Then
    ' do something
    ' do something else
End If

To translate that to C# and properly execute the 2 lines of code you should use braces:

if (condition)
{
    // do something
    // do something else
}

Your current translation actually looks like this:

if (condition)
    // do something (if condition is true)
// do something else (not dependent on the condition)

In other words the 2nd statement always executes. It’s a good practice to always enclose multiple statements within the braces to avoid such unintended circumstances.

Change your code to this:

if (!((row.RowState & DataRowState.Deleted) == DataRowState.Deleted))
{
    item = row["albumCode"] + ", " + row["AlbumTitle"] + ", " +                                row["ArtistCode"];
    //list rows with update errors
    if (row.HasErrors)
    {
        item = "(**" + row.RowError + "**)";
    }

    lstAlbums.Items.Add(item);
}

//list deleted rows
if ((row.RowState & DataRowState.Deleted) == DataRowState.Deleted)
{
    delitem = row["albumCode", DataRowVersion.Original] + ", " 
        + row["AlbumTitle", DataRowVersion.Original] + ", " 
        + row["ArtistCode", DataRowVersion.Original] + "***DELETED***";
    lstAlbums.Items.Add(delitem);
}