Question

I want to create two dimensional array of buttons in windows form. I have to do it with for loops because I want to have an array of 100 buttons. But I cant get it to work. I tried with List> and with Buttton[,] but doesn’t work. When I try like this:

private List<List<Button>> LEDarray = new List<List<Button>>();

        for (int y = 0; y < 5; y++)
        {
            this.tempList.Clear();

            for (int x = 0; x < 20; x++)
            {
                this.tempList.Add(new Button());
            }

            this.LEDarray.Add(tempList);
        }
        for (int y = 0; y < 5; y++)
        {
            for (int x = 0; x < 20; x++)
            {
                this.LEDarray[y][x].BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(0)))), ((int)(((byte)(64)))), ((int)(((byte)(0)))));
                this.LEDarray[y][x].FlatStyle = System.Windows.Forms.FlatStyle.Flat;
                this.LEDarray[y][x].ForeColor = System.Drawing.Color.Black;

                xPos = xOffset + LEDsize * x + 20;
                yPos = yOffset + LEDsize * y + 20;

                this.LEDarray[y][x].Location = new System.Drawing.Point(xPos, yPos);
                this.LEDarray[y][x].Name = "button" + y.ToString() + x.ToString(); 
                this.LEDarray[y][x].Size = new System.Drawing.Size(LEDsize, LEDsize);
                this.LEDarray[y][x].TabIndex = 0;
                this.LEDarray[y][x].UseVisualStyleBackColor = false;
            }
        }

        for (int y = 0; y < 5; y++)
        {
            for (int x = 0; x < 20; x++)
            {
                this.Controls.Add(this.LEDarray[y][x]);
            }
        }

It only display the last row of buttons. So just fifth row and not the previous one. When I try similar with Button array it does not work at all. But array way is just SOS call. I want to do it with List so can you help me with code above to make it work?

Answer 1

Change condition for (int y = 0; y < 0; y++) to for (int y = 0; y < 5; y++) when adding buttons to controls.

Second problem is that you are clearing your tempList, reference to which you just added to LEDarray. Create new list for each row of buttons:

for (int y = 0; y < 5; y++)
{
     // tempList.Clear() - this will remove all buttons from previous row
     tempList = new List<Button>();

     for (int x = 0; x < 20; x++)     
          tempList.Add(new Button());     

     LEDarray.Add(tempList);
}

Also I’d recommend you to increment TabIndex for buttons:

this.LEDarray[y][x].TabIndex = 10 * y + x;

And another advise – create your custom LEDButton class and use it:

public class LEDButton : Button
{
    public const int LEDWidth = 20;
    public const int LEDHeight = 20;

    public LEDButton()
    {
        BackColor = Color.FromArgb(0, 64, 0);
        ForeColor = Color.Black;
        FlatStyle = FlatStyle.Flat;
        Size = new Size(LEDWidth, LEDHeight);
        UseVisualStyleBackColor = false;
    }
}

Usage:

// initialize array
LEDButton[,] leds = new LEDButton[5, 20];
for (int y = 0; y < leds.GetUpperBound(0); y++)
    for (int x = 0; x < leds.GetUpperBound(1); x++)
        leds[y, x] = new LEDButton()
            {
                Name = String.Format("Button{0}{1}", y, x),
                TabIndex = 10 * y + x,
                Location = new Point(LEDButton.LEDWidth * x + 20,
                                     LEDButton.LEDHeight * y + 20)
            };
// add buttons to controls
for (int y = 0; y < leds.GetUpperBound(0); y++)
    for (int x = 0; x < leds.GetUpperBound(1); x++)
         Controls.Add(leds[y, x]);