Textbox converts input into currency value

I'd approach this in three steps:

1. if I had thoroughly examined every possible use of a MaskedTextBox, with setting the 'Culture property to "eu-ES", so that, theoretically, I could get results in € vs. US $ ... and was not satisfied with the result ...

... then ...

2. if I had searched CP, and the net, for somebody already having worked out an elegant solution for this, and I did not find something already adequate:

... then ...

3. I'd create a UserControl that contained two NumericUpDown Controls, both with the 'DecimalPlaces property set to #0. The left one would hold the integer Pound amount, the right the integer that will become the fractional part of the return value.

a. I'd create a Public Property of Type Decimal to make the result available to outside consumers of the UserControl.

b. I'd set the right NumericUpDown to have a Minimum value of #0, and a Maximum value of #99.

c. I'd set the Maximum value of the left NumericUpDown to the largest possible amount I wanted to allow to be entered, and its Minimum to #0,

d. In that UserControl I'd "wire up" the same KeyPress EventHandler to both NumericUpDown Controls: in that KeyPress EventHandler (as shown below): I'd intercept the Enter key

e. On the Enter key being pressed: I'd update the Public property described in "3a." above. Dividing the right NumericUpDown control value by #100 to get the "decimal part" (as shown below).

The code might look like this:

namespace TestCurrencyEntry
{
    public partial class MyPoundEntry : UserControl
    {
        public MyPoundEntry()
        {
            InitializeComponent();
        }

        public decimal ResultInPounds { get; set; }

        // assign KeyPress Event of both NumericUpDown Controls to this
        private void PoundEntry_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                ResultInPounds = numericUpDown1.Value + (numericUpDown2.Value/100);

               // perform extra validation here ?

               // raise an Event here ?
            }
        }
    }
}

Discussion:

1. I'd consider on Entry into the UserControl setting the Focus to the Left NumericUpDown Control.

2. Given the two NumericUpDown Controls are in the proper tab-order, then you can easily start entering the integer amount in the left NUD control, then, hit the tab-key, and continue entering the integers in the right NUD that will become the decimal amount.

3. Depending on application requirements, I might want to raise an Event whenever the value was changed.

You can always select text direction using System.Windows.Forms.TextBox.RightToLeft; see also a number of RtlTranslate… methods, http://msdn.microsoft.com/en-us/library/system.windows.forms.textbox.aspx[^].

WPF provides different ways to support input direction, see http://msdn.microsoft.com/en-us/library/aa350685.aspx[^].

I found your description of input contradictory though: putting cursor on right means normal left-to-write method, your example confirms it. Anyway, from this answer you can find our what you need, experiment with input.

—SA