将文本框传递给方法。 使用textchanged事件时。 C＃Visual Studio

Question

I have a text box on my form which I am trying to add some validation to. I've attached the following method to the textchanged event. However I'm getting a 'no overload for method matches system.EventHandler' error. I don't really understand why I'm getting it. Am I not passing the arguments to the method when I call it?

        private void rangeValidate(TextBox textbox)
        {

            int mark = Convert.ToInt32(textbox.Text);
            if (mark >= 0 & mark >= 100)
            {
                MessageBox.Show("Please enter a number betwen 0 and 100");
            }

        }

Answer 1

If you attached this method:

private void rangeValidate(TextBox textbox)

to TextChanged , you need to conform to the delegates signature. So, change it like this:

private void rangeValidate(object sender, EventArgs e)
{
    TextBox textbox = sender as TextBox;
    int mark = Convert.ToInt32(textbox.Text);
    if (mark >= 0 & mark >= 100)
    {
        MessageBox.Show("Please enter a number betwen 0 and 100");
    }
}

Answer 2

You can also declare this function like:

protected void rangeValidate(object sender, EventArgs e)

and add event in the pageload for the textbox, say TextBox1 as

TextBox1.TextChanged += rangeValidate;