Regex which allow minus (-) sign only
c#, decimal, regex, validation, winforms
Solution
You need to escape the minus sign because `-` is a special character.
Try `(\+|\-)?` (note the backslash).
Edit: Not sure if this will do what you want, but it's a lot simpler:
`^\-?\d*\.?\d*$`
Will match any decimal (1 to infinite chars on either side of a decimal, with or without a -). More details here: http://regex101.com/r/rP7cG2
Problem
I am using this regex to validate input strings as `decimal` values in Textbox. `^\d{1,16}((\.\d{1,4})|(\.))?$` Now I want to allow `negative decimal` values. I have found many similar questions on SO. And I tried something like these: `/^-?`, `(\+|-)?`, `\.\d{1,4}\-` but not working. The reason I asked a new question here because I am using Textbox `TextChanged` event and I need to check each character entered into the Textbox. So the first character, minus(-) sign, should be valid Valid Values: Positive Values - `1` - `1.` - `1.1` - `1.1111` Negative Values - `-` - `-1` - `-1.` - `-1.1` - `-1.1111` The Regex that I have above validate for positive values. How can I modify my Regex to allow negative values? Any help will be very much appreciated.