I'd like to have a regex, which only allows digits between 0.0 and 1.0 in a textbox.
BUT it should be in the method PreviewTextInput (C#, WPF project)
So the normal regex doesn't work
Regex regex = new Regex(@"^0|0.0|0\.[0-9]*|1\.0|1$");
I've found a regex, which allows all decimals in the PreviewTextInput method:
Regex regex = new Regex("^[.][0-9]+$|^[0-1.]*[.,]{0,1}[0-9]*$");
How can a change this regex to only accept decimals between 0-1?
Thanks.
My method for decimals:
private void tb_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
Regex regex = new Regex("^[.][0-9]+$|^[0-1.]*[.,]{0,1}[0-9]*$");
e.Handled = !regex.IsMatch((sender as TextBox).Text.Insert((sender as TextBox).SelectionStart, e.Text));
}
My method for decimals between 0-1 (doesn't work):
private void tb_Surface_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
Regex regex = new Regex(@"^(0?\.[0-9]+|1\.0)$");
e.Handled = !regex.IsMatch(e.Text);
// e.Handled = !regex.IsMatch((sender as TextBox).Text.Insert((sender as TextBox).SelectionStart, e.Text));
}
@"^(0(?:\.\d+)?|1(?:\.0+)?)$"
0 and 1 also can be matched,if you don't want match them,and must have any digits after dot ,you can use
@"^(0\.\d+|1\.0+)$"
The code below is what you want,and you need to remove the last dot when the textbox lost focus,such as str.Trim('.')
private void tb_Surface_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
var patten = @"^(0(\.\d*)?|1(\.0*)?)$";
Regex regex = new Regex(patten);
e.Handled = !regex.IsMatch(e.Text);
// e.Handled = !regex.IsMatch((sender as TextBox).Text.Insert((sender as TextBox).SelectionStart, e.Text));
}
About @"^0|0.0|0\.[0-9]*|1\.0|1$": there are two mistakes:
1) one of the dot is not escaped, so it can match any characters.
2) The ^ and $ are only respectively in the first and last branches of your alternation, but are not in factor with each branch. To do that you must put all branches in a non capturing group.
About "^[.][0-9]+$|^[0-1.]*[.,]{0,1}[0-9]*$": the first branch is ok, the second branch is false.
1) [0-1.]* that can be written [01.]* (there is no characters between 0 and 1, no need to put a range) allow any combination of 0, 1 and .: 1111111111, 10100010 or 1.00.111... Not sure that allowing the dot here is a good idea.
2) [.,]{0,1} that can be written [.,]?: why this time you want to allow the comma?
3) [.,]{0,1}[0-9]*$ if the dot (or the comma) is optional, this subpattern can match any integer because of the [0-9]*.
I think you must consider using non-capturing groups to build your pattern. Starting from your first pattern seems to be the best option. Anyway, the first job is to clearly define what are the allowed formats.
