RegEx for decimal with N-digit precision

Question

I would like to validate a decimal in the below range in my MVC3 application.

0.000000001 to 100.000000000

This is the Regex I tried but, it is not working:

(^100([.]0{1,9})?)$|(^\\d{1,9}([.]\\d{1,9})?)$

  [RegularExpression(@"(^100([.]0{1,9})?)$|(^\d{1,9}([.]\d{1,9})?)$", 
   ErrorMessage ="Decimal value should be between 0.000000000 to 100.000000000")]
  [Range(0, 100, ErrorMessage = " % must be between {1} and {2}")]
  [Display(Name = "Percentage:")]
  public double? Percentage { get; set; }

Can anyone see what I am doing wrong?

Answer 1

^(1\d\d|[1-9]\d|\d)\.\d{0,8}[1-9]$

Answer 2

In your second alternative you allow 1 to 9 digits before the dot.

(^100([.]0{1,9})?)$|(^\d{1,9}([.]\d{1,9})?)$
                           ^

Change this to

^(100(\.0{1,9})?|\d{1,2}(\.\d{1,9})?)$

You can still "simplify" this, by moving the fraction out of the alternation

^(100|\d{1,2})(\.\d{1,9})?$

be aware that this expression does allow leading zeros like "00.1".

See it here on Regexr

Answer 3

我相信这应该可以解决问题。

\d+\.\d{9}

Answer 4

This will be the required regex:

(\d|[1-9]\d)(\.\d{1,9})?|100(\.0{1,9})?

In your regex, (^\\d{1,9}([.]\\d{1,9})?)$ matches one to nine digits (may be nine 0s upto nine 9s) followed by optional decimal part. This is the problem.

Answer 5

^(?:(?:[1]\d)|(?:[1-9]))?\d\.\d{9}$

This will match your range. Also, it will not match the odd scenario of a double zero preceding the decimal like such: 00.000000000. So, 00.000000000 will not be a valid number.

If you want it with variable decimal places to the right of the 0, then you can use something like:

^(?:(?:[1]\d)|(?:[1-9]))?\d\.\d{1,9}$

edit: sentence wording