仅与正则表达式匹配浮点数

Question

I have a working regex that matches floating point as well as integer but I need one to only match floating point (number of decimals can be any).

This is what I have so far

 Regex regex = new Regex(@"^-?(?=.*[1-9])\d+(\.\d+)?$", RegexOptions.IgnoreCase);

How do I mod it to only match the floating point?

Answer 1

The regex you're looking for is (I've split it into groups for the explanation):

Regex regex = new Regex(@"^(\+?)([0-9]*)(\.)([0-9]+)$");

Explanation:

• Group 1 - an optional plus sign at the beginning.

• Group 2 - optional digits before the dot (why optional? because, for example, .345 is a valid number - and stands for 0.345 ).

• Group 3 - the decimal dot.

• Group 4 - numbers after the dot. One comment: This regex will accept numbers such as 12345.0 although is not a really decimal. I don't see how to solve this just with regex (without code).

Answer 2

I think you need this one

Regex regex = new> Regex(@"^([-+]?)(([0]{1})|([1-9]+([0-9]*)))(\.)([0-9]+)$");

• Group 1: Optional "-" sing on the begin.
• Group 2 - 5: The number begin whit 0 OR begin whit another num (1-9) one or more. In this Case is not posible to match (EX: 001.55 - It's not a float number).
• Group 6 - Include "."
• Group 7 - Include one or more (0-9)