Regexp to Validate a Non-Zero Number

regexp to validate a non-zero number

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

https://regex101.com/r/wHZUoW/1

-Since you don't want the number to start with 0, you shouldn't make the [1-9] at the beginning optional with ?.

-As general good practice, a non-capturing group (?: ... ) is used instead of a capturing group, because the contents do not need to be referenced later.

Javascript Regular Expressions - accept non-zero for first number in amount

If you want to check if the first value value isn't zero, you can simply do a substr:

Inputvalue.substr(0,1) !== '0'

If you want all leading zeroes replaced:

Inputvalue.replace(/^0+/, '');

The ^ means 'string begins with', then 'one or more' (+) zeroes.

If you want all leading zeroes before a digit(\d) replaced:

Inputvalue.replace(/^0+\d/, '');

The ^ means 'string begins with', then 'one or more' (+) zeroes.

If you want to get the first digit after the zeroes:

The ^ character means 'start of string'. You say it could be 000001, the 1 is not at the start of the string, so that will never match.

I find it helpful to define what I want in text:

I want the first digit, only one -> [1-9]
Starts with ^{(^)} with one or more ⁽⁺⁾ zeroes -> ^0+

That results in ^0+[1-9].

We only want to store the digit, so we place that in a group: ^0+([1-9])

const examples = [  '123', // no starting zeroes  '0123', // match  '000123', // match  '132000123', // no matching zeroes, dont match the end either!];
console.log(examples.map(function (example) {  const matches = example.match(/^0+([1-9])/);  return example + ' -> ' + (matches !== null ? matches[1] : 'no match!');}));

Regex for any non-zero number

^.{16}(?!00000)

Use negative look around to find the next five characters that are not 00000

Regular expression to match a non-zero, zero-padded integer

Why not using this:

^0*[1-9][0-9]*$

?
Btw, you missed to specify the regex engine in use. But the above pattern should work in almost any regex engine.

Regular expression for non-zero positive floats

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

JavaScript match numbers that are not zero or start with zero

You need to specify a * after second [0-9] to match zero or more digits. In addition to one digit numbers, this will also fail to match more than two digit numbers. Correct regular expression is ^[1-9][0-9]*.

regex c# expression to validate all numbers except zero

Use this expression to accept zero (0) or any negative number up to 4 digits:

@"^(0|-[1-9]\d{0,3})$"

If you also want to accept -0, -0123 and the likes, you can use:

@"^(0|-\d{1,4})$"

finding non zero values in the string using regular expression (regex)

You can use

(?<=_)(?![0.]+_)\d+\.\d+

See the regex demo.

Details

(?<=_) - a _ must occur immediately to the left of the current location
(?![0.]+_) - immediately to the right, there cannot be only zeros and .
\d+\.\d+ - one or more digits, ., one or more digits.

You can also use

(?<!\d)(?!0+\.0+(?!\d))\d+\.\d+

See this regex demo. Details:

(?<!\d) - a left-hand digit boundary
(?!0+\.0+(?!\d)) - no one or more zeros, ., one or more zeros not followed with a digit are allowed immediately to the right of the current location
\d+\.\d+ - one or more digits, ., one or more digits.

Regexp to Validate a Non-Zero Number