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hi currently I'm working on a Point of sale software in c# with SQL Server I just make a form to receive the Invoice amount in this screen cashier enters the paid amount.
but I did not know how can I add auto point function just like a cash register,
let suppose cashir want to enter 180.78 but i want
if the user press 1 then in the text box it write 0.01
when the user press 5 then 0.15
and when the user press 0 the 1.50
when the user press 7 then 15.07
when the user press 8 then 180.78 etc
I hope you understand my condition please any one tell me how can I achieve this,
thanks in advance

What I have tried:

i dont know how can i do this, please any one suggestion me any method
Updated 6-Nov-21 10:30am

You can use the Masked Textbox for this with the RightToLeft property set to yes, see:
How to Mask input in MaskedTextBox in C#? - GeeksforGeeks[^]

But you probably want to write your own custom control, here is an example:
Masked C# TextBox Control[^]
BillWoodruff 6-Nov-21 17:34pm
You will need the TextChanged event.
A regular textbox takes a bit of string manipulation, something like this:

private void tb_TextChanged(object sender, EventArgs e) {
	string s = tb.Text;
	s = "000"+s.Replace(".", "");
	int len = s.Length;
	s = s.Substring(0, len-2).TrimStart('0').PadLeft(1, '0')+
	tb.Text = s;
	tb.SelectionStart = s.Length;
	tb.SelectionLength = 0;

- textbox can initially be empty (does not need to be initialized to 0.00)
- does not rely on numeric conversions, so no range limitations
- works also when something gets pasted in
- does not reject unexpected characters (if needed, extra code should be added)
- textbox cursor is forced to the right
- fortunately this event only fires when the content really changes, so no event avalanche (unless the event handlers code isn't stable)
- during development it is wise to add logging and to apply a simple defense, e.g.

private void tb_TextChanged(object sender, EventArgs e) {
	if (++changes>10) return;

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