C#在键入时突出显示文本框中的当前字符

Question

当我单击或专注于文本框选择时，我编写了这段代码选择字符突出显示 但是当我输入（编辑）突出显示时（文本框有默认文本）

        textBox1.GotFocus += textbox1_OnFocus;

    private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && (e.KeyChar != '.'))
        {
            e.Handled = true;
        }

        // only allow one decimal point
        if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
        {
            e.Handled = true;
        }

        textBox1.SelectionStart = textBox1.SelectionStart;
        textBox1.SelectionLength = 1;

    }

     private void textbox1_OnFocus(object sender, EventArgs e)
    {
        textBox1.Focus();
        textBox1.SelectionStart = 0 ;
        textBox1.SelectionLength = 1;

    }

    private void textBox1_MouseClick(object sender, MouseEventArgs e)
    {
        listBox1.Items.Add(textBox1.SelectionStart);
        textBox1.SelectionStart = textBox1.SelectionStart;
        textBox1.SelectionLength = 1;
    }

如何编辑我的代码以获得正确答案？

Answer 1

我写了它，但我认为这不是好方法

        private void textBox1_KeyUp(object sender, KeyEventArgs e)
    {
        textBox1.SelectionStart = textBox1.SelectionStart;
        textBox1.SelectionLength = 1;
    }