Check decimal and total length of number

Question

Using regex, I can check if it is decimal or not

^\d*\.?\d*$

But what I want to control is total length of those digit.

(^\d*\.?\d*$){1,10}

But I still cannot control it.

After 2 days later, my final solution is

(?=^\d*\.?\d*$)^.{1,10}$

Debuggex Demo

Answer 1

Here's a solution:

^(?!.{10})\d*\.?\d*$

This will check the whole number isn't more than 10 characters.

If you want to check the whole number isn't more than 10 digits (not counting the dot), you may use

^((?!.{11})\d*\.\d*|(?!.{10})\d*)$

Answer 2

(^\d*\.?\d*$){1,10}
    ↑     ↑

The * means, zero or more. So your regex means "zero or more times, from 1 to 10 times", so {1,10} in this case is redundant. You need to remove * or apply {1,10} only to parts that doesn't have it.

For example, you can change your regex to:

^\d*(\.?\d{0,10})$

This matches numbers that has up to 10 digits after the dot. If you want to match a float number that has 10 digits in total, you can use negative lookahead (as @DenysSéguret already mentioned in his answer +1):

(?!.{10})\d*\.?\d*

It matches \d*\.?\d*$ only if it its length < 10 (including the dot).