c# - how to load a value in textbox at program startup

Question

i managed to do somehow what i want by doing this

    private void textBox1_Enter(object sender, EventArgs e)
    {
        textBox1.Text = "a1";
    }

But i want this to happen without clicking on the textbox The way i did upper required me to click before a1 will be written there.

Answer 1

Loadフォームのイベントでそれを行う必要があります

private void YourFormName_Load(object sender, EventArgs e)
{
     string someValue="Get the value from wherever you want";
     textBox1.Text = someValue;
}

Answer 2

たとえば、 appsetting で config のグローバル変数を読み取る必要がある場合

NameValueCollection appSettings = ConfigurationManager.AppSettings;
textBox1.Text = appSettings["yourkey"];