Do we have to repeat our code in a WinForms application?

Question

So I'm trying to switch from C# console to form, but I always read that never repeat our code etc.

My first project would be a calculator, and I found a site just to take a look how it looks like in win form, but in this code there are a lot of repeating. Is this normal in form, in let's say a calculator?

Here is the link that I am talking about.

Answer 1

That is a lot of repetition, to improve it add one click event handler for all of the buttons, eg:

btn1.Click += btnClick;
btn2.Click += btnClick;

Then cast the sender to a Button to get which one was clicked, a rough example:

private void btnClick(object sender, EventArgs e)
{
    var btnName = ((Button)sender).Name;
    var btnValue = btnName.Replace("btn",string.Empty);

    if (textBox1.Text == "0" && textBox1.Text != null)  
    {  
        textBox1.Text = btnValue;  
    }  
    else  
    {  
        textBox1.Text = textBox1.Text + btnValue;  
    }  
}

Don't forget to unhook the event subscriptions in the form unload event:

btn1.Click -= btnClick;
btn2.Click -= btnClick;