Custom Control: Numeric TextBox: TextBox that alow you to enter only numbers

Introduction

Sometimes we need to control the user input. This control is a normal TextBox, with the property that the control accept only numeric values!

because this control is a TextBox, we inherit from the base class like this NumericTextBox : TextBox

What we have to do is to override the events OnKeyPress and OnKeyDown for the control. The full code is this:

using System.Windows.Forms;
using System.ComponentModel;

namespace MyCustomControls
{
    [Description("Numeric TextBox")]
    public class NumericTextBox : TextBox
    {
        private bool nonNumberEntered = false;

        public NumericTextBox()
        {
            this.Width = 150;
        }

        protected override void OnKeyPress(KeyPressEventArgs e)
        {
            if (nonNumberEntered == true)
            {
                e.Handled = true;
            }
        }
        protected override void OnKeyDown(KeyEventArgs e)
        {
            nonNumberEntered = false;
            if (e.Shift == true || e.Alt == true)
            {
                nonNumberEntered = true;
                return;
            }
            if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
            {
                if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
                {
                    if (e.KeyCode != Keys.Back)
                    {
                        nonNumberEntered = true;
                    }
                }
            }
        }
    }
}

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