Textbox that accepts only floating values with only one decimal in the value

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2.00/5 (1 vote)

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Hi,

Can any one help me in generating the regex for only acceptable floating values where one can only able to add one decimal inside value

For Ex:-

12.5 -------------Allowed to type
12.5. -------------Don't allowed to type second decimal
12 -------------Allowed without any decimal
.12 -------------Allowed decimal in first place
12. -------------It's also ok to allow

I have one regex which accepts floating values i.e :-
Regex regex = new Regex("[^0-9.]+");

But the problem in it is that you can enter more than one decimal.
Any Solution.....

Thanks In Advance

Posted 17-Mar-15 9:57am

binadi007

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Comments

Zoltán Zörgő 17-Mar-15 16:00pm

Why is this allowed, it has two decimals?
.12 -------------Allowed decimal in first place

binadi007 17-Mar-15 16:11pm

only one decimal i.e ".", where is it two time
Here decimal means period

Sergey Alexandrovich Kryukov 17-Mar-15 16:36pm

What is the exact TextBox type? Full name, please.
—SA

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**Zoltán Zörgő** · Accepted Answer · 2015-03-17T10:03:00

Solution 1

I think this expression will do it:
\d*\.?\d?

Posted 17-Mar-15 10:03am

Zoltán Zörgő

Comments

binadi007 17-Mar-15 16:12pm

"\" shows red line below it how to write "\" symbol?

Richard Deeming 17-Mar-15 16:16pm

For C#, you'll either need to escape the \ character:
"\\d*\\.?\\d?"
or use a verbatim string:
@"\d*\.?\d?"

binadi007 17-Mar-15 16:23pm

still shows error......incorrect regex for floating values with only one "."

Zoltán Zörgő 17-Mar-15 16:29pm

It is correct, but try this:
@"^\d*\.?\d?$"
You were not using it correctly...

binadi007 17-Mar-15 16:38pm

It's not right.....I tried it and still able to write alphabets in the textbox,
Where with this code :- "[^0-9.]+"
I'm not able to write alphabets

Zoltán Zörgő 17-Mar-15 16:45pm

It is. Show me the code.
[^0-9.]+ means: anything that is not 0123456789.

binadi007 17-Mar-15 16:51pm

My Function Is :-
public static bool FloatValue(string text)
{
Regex regex = new Regex(@"^\d*\.?\d?$");

/*Plz Uncomment below line which is working*/
//Regex regex = new Regex("[^0-9.]+");
return !regex.IsMatch(text);
}

Call this function in PreviewTextInput event like :-

private void txtTest_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
e.Handled = !FloatValue(e.Text);
}

Zoltán Zörgő 17-Mar-15 17:50pm

Don't you see, that you are negating the result before returning?


public static bool isFloatValue(string text)
{
Regex regex = new Regex(@"^\d*\.?\d?$");
return regex.IsMatch(text);
}
	
void Main()
{
	Console.WriteLine(isFloatValue("12.5"));
	Console.WriteLine(isFloatValue("12.5."));
	Console.WriteLine(isFloatValue("12"));
	Console.WriteLine(isFloatValue(".1"));
	Console.WriteLine(isFloatValue("12."));
}

Will yield

True
False
True
True
True

As you wanted.

Zoltán Zörgő 18-Mar-15 2:03am

well?

BillWoodruff 18-Mar-15 3:27am

+5 nice work.

binadi007 18-Mar-15 10:36am

Yeah Zoltan, really it's working in console application from my side too. But In which event I applied to get the same output that u define.
As I'm right now using PreviewTextInput event. In that I use e.Text which just check one char at a time So I didn't able to get the same result as u provide.
BTW I'm using WPF. Any solution for right event ?

Zoltán Zörgő 18-Mar-15 14:18pm

Well, for wpf input validation you can use this nice approach: http://www.codeproject.com/Articles/15610/Regex-Validation-in-WPF.