Textbox for price/cash/currency on C#

Question

I have a problem that is haunting me for a while. I tried some solutions but they didn\'t worked.

I have a textbox that is for cash input ($999,99 for example). Howe

Answer 1

Some people might want to actually format a textbox as they type. So this is my solution if anyone is looking for one.

It actually assumes you are entering one digit at a time so therefore as you press "1" it assumes "$0.01" and when they press "2" it then assumes "$0.12" and so on and so forth.

I could not find anything online about formatting as they typed. It has been tested and if any errors let me know.

private void textBox1_TextChanged(object sender, EventArgs e)
{
    //Remove previous formatting, or the decimal check will fail including leading zeros
    string value = textBox1.Text.Replace(",", "")
        .Replace("$", "").Replace(".", "").TrimStart('0');
    decimal ul;
    //Check we are indeed handling a number
    if (decimal.TryParse(value, out ul))
    {
        ul /= 100;
        //Unsub the event so we don't enter a loop
        textBox1.TextChanged -= textBox1_TextChanged;
        //Format the text as currency
        textBox1.Text = string.Format(CultureInfo.CreateSpecificCulture("en-US"), "{0:C2}", ul);
        textBox1.TextChanged += textBox1_TextChanged;
        textBox1.Select(textBox1.Text.Length, 0);
    }
    bool goodToGo = TextisValid(textBox1.Text);
    enterButton.Enabled = goodToGo;
    if (!goodToGo)
    {
        textBox1.Text = "$0.00";
        textBox1.Select(textBox1.Text.Length, 0);
    }
}

private bool TextisValid(string text)
{
    Regex money = new Regex(@"^\$(\d{1,3}(\,\d{3})*|(\d+))(\.\d{2})?$");
    return money.IsMatch(text);
}

To make it look nice I'd recommend starting the text box with the text $0.00 on the form load like so:

    private void Form1_Load(object sender, EventArgs e)
    {
        textBox1.Text = "$0.00";
        textBox1.SelectionStart = inputBox.Text.Length;
    }