Correct way to add controls dynamically

Question

CheckBox[] checkBoxArray = new CheckBox[lines.Count()];
CheckBox checkBox = new CheckBox();

int yLocation = 25;
int diff = 0;
int i = 0;
foreach(var line in lines)
{
    this.checkBox.Text = line;
    this.checkBox.Location = new System.Drawing.Point(90, yLocation + diff);
    this.checkBox.Size = new System.Drawing.Size(110, 30);
    checkBoxArray[i] = checkBox;
    i++;
    diff = diff + 30;
}

I debugged my app and checkBoxArray (after the loop) is all the same.

The second issue is how do I add my controls to the WinForm?

Answer 1

It looks like you're actually working with some class-level member called checkBox instead of the locally-scoped one:

CheckBox[] checkBoxArray = new CheckBox[lines.Count()];

int yLocation = 25;
int diff = 0;
int i = 0;
foreach(var line in lines)
{
    CheckBox checkBox = new CheckBox();
    checkBox.Text = line;
    checkBox.Location = new System.Drawing.Point(90, yLocation + diff);
    checkBox.Size = new System.Drawing.Size(110, 30);
    checkBoxArray[i] = checkBox;
    i++;
    diff = diff + 30;
    Controls.Add(checkBox);  // Add checkbox to form
}

I'm not sure what the purpose of the checkBoxArray is, but if it was just an attempt to get things working, you can safely get rid of it.

Answer 2

If you don't create a new CheckBox instance inside the loop, then you're just overwriting the values on the same CheckBox again and again.

foreach (var line in lines)
{
    // Create a new CheckBox
    var checkBox = new CheckBox();

    // Set its properties
    checkBox.Text = line;
    ...

    // Add it to the form's collection of controls
    this.Controls.Add(checkBox);

    // Adjust checkBox.Location depending on where you want it
    checkBox.Location = new Point(0, 0);
}

Answer 3

Maybe this helps you a bit: http://support.microsoft.com/kb/319266

this.Controls.Add(checkBox);