CODEWITHSUNDEEP
javascriptregex
regretwary
regretwary

Reputation: 53

Regular expression for non-zero positive floats

Regex for positive float numbers provides almost the correct expressions, but all of them include 0.0 and 0. Closest desired expression is: ^(?:[1-9]\d*|0)?(?:\.\d+)?$ but this includes 0.0 and 0.

What is the regex expression for positive floating numbers such as:

1.0
1.1
0.1
11

but do not include floating numbers such as:

0.0
-0.0
0
-1.0
-1.1
-0.1
-11

Upvotes: 4

Views: 1616

Answers (3)

Anton L.
Anton L.

Reputation: 828

This one is the best:

^\.0*[1-9]\d*$|^0(\.0*[1-9]\d*)$|^[1-9]\d*?(\.\d+)?$

See how it works on regex101.

If you don't want to accept floats like .5, use this one:

^0(\.0*[1-9]\d*)$|^[1-9]\d*?(\.\d+)?$

Upvotes: 1

EJoshuaS - Stand with Ukraine
EJoshuaS - Stand with Ukraine

Reputation: 12191

The accepted answer from the linked question can be adapted by removing the choice of 0 from the first group, and choosing between that group and another group that starts with 0.

^(((?:[1-9]\d*)?(?:\.\d+)?)|(0\.[1-9]\d*))$

This works too:

^((([1-9]\d*)(\.\d+)?)|(0\.[1-9]\d*))$

Basically, this is "saying" that if the number starts with 0, it has to be followed by a dot and something other than 0. After that, any digit is permissible. So, 0 and 0.0 aren't permitted, but 0.1 and 0.10 are.

Note: This Regex will not permit leading 0s. So, for example 101.0 is permissible but 0101.0 is not.

Edit: The following will allow for cases like 0.01:

^((([1-9]\d*)(\.\d+)?)|(0\.[1-9]\d*)|(0\.0+[1-9]+\d*))$

Upvotes: 0

Ryszard Czech
Ryszard Czech

Reputation: 18641

Use

^(?:[1-9]\d*|0(?!(?:\.0+)?$))?(?:\.\d+)?$

See proof.

Explanation

--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
--------------------------------------------------------------------------------
    [1-9]                    any character of: '1' to '9'
--------------------------------------------------------------------------------
    \d*                      digits (0-9) (0 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
   |                        OR
--------------------------------------------------------------------------------
    0                        '0'
--------------------------------------------------------------------------------
    (?!                      look ahead to see if there is not:
--------------------------------------------------------------------------------
      (?:                      group, but do not capture (optional
                               (matching the most amount possible)):
--------------------------------------------------------------------------------
        \.                       '.'
--------------------------------------------------------------------------------
        0+                       '0' (1 or more times (matching the
                                 most amount possible))
--------------------------------------------------------------------------------
      )?                       end of grouping
--------------------------------------------------------------------------------
      $                        before an optional \n, and the end of
                               the string
--------------------------------------------------------------------------------
    )                        end of look-ahead
--------------------------------------------------------------------------------
  )?                       end of grouping
--------------------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
--------------------------------------------------------------------------------
    \.                       '.'
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
  )?                       end of grouping
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

Upvotes: 2

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