How to allow inside a textbox in winforms C#

Question

1.00/5 (1 vote)

See more:

How to allow inside in textBox1 next items:
- allow only numbers (0-9)
- also allow next letters: M B G T
- also allow: the dot "." and comma ","

What I have tried:

C#

 private void textBox1_TextChanged(object sender, EventArgs e)
        {
//
        }

Posted 18-Mar-20 5:43am

Member 10410972

Updated 18-Mar-20 10:41am

Add a Solution

Comments

Richard MacCutchan 18-Mar-20 12:20pm

Just add your code where the comment marker is.

gggustafson 18-Mar-20 13:37pm

I think you are capturing using the wrong event. From Microsoft "Occurs when the Text property value changes." That's not going to allow you to test individual characters as they are entered into the TextBox. I'd suggest that you consider the KeyDown event. It provides information about the key that has been pressed BEFORE the value is displayed. Thus you can test the key and inhibit its display. Hope that helps.

2 solutions

Solution 1

We are more than willing to help those that are stuck: but that doesn't mean that we are here to do it all for you! We can't do all the work, you are either getting paid for this, or it's part of your grades and it wouldn't be at all fair for us to do it all for you.

So we need you to do the work, and we will help you when you get stuck. That doesn't mean we will give you a step by step solution you can hand in!
Start by explaining where you are at the moment, and what the next step in the process is. Then tell us what you have tried to get that next step working, and what happened when you did.

Just writing the method signature ans expecting us to "fill it in" isn't going to get you anywhere.
Hint: I'd use a Regex.

Posted 18-Mar-20 6:13am

OriginalGriff

v2

Comments

Member 10410972 18-Mar-20 12:39pm

Ok, sorry, forget it ... I'll handle it myself.

OriginalGriff 18-Mar-20 12:44pm

Excellent - you'll learn more that way anyway!

gggustafson 18-Mar-20 13:40pm

I don't like your attitude! This site is to help, not embarrass OPs. Yes, we acknowledge that you are knowledgeable. But there is absolutely no reason to cause discomfort to an OP. A simple answer, like mine, goes a long way to improve OP's knowledge base.

Maciej Los 18-Mar-20 16:50pm

Not sure why some one down-voted your answer, Paul...
Up-voted!

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Maciej Los · Accepted Answer · 2020-03-18T10:42:00

I'd suggest to use validate event with ErrorProvider and Regex.

Here is a complete example: Control.Validating Event (System.Windows.Forms) | Microsoft Docs[^]

C#

string[] somestrings = {"Ads20.e", "MG20.9", "BT3,5.0", "mt29.00", "32TG,5.99", "58BM5.11"};
string pattern = @"[[M|G|B|T|][0-9]|\.\,]|[[0-9][M|G|B|T|]|\.\,]";

foreach(string s in somestrings)
{
	Console.WriteLine("{0} => {1}", s, Regex.IsMatch(s, pattern));
}

Result:

Ads20.e => False
MG20.9 => True
BT3,5.0 => True
mt29.00 => False
32TG,5.99 => True
58BM5.11 => True