What's the regular expression for positive whole numbers only? (zero is not allowed)

Question

I was able to get the regular expression for numbers only which is ^\d+$. I've been trying to look for one online but it's already been an hour so I've decided to post it here on Stack Overflow.

matches:

1 || 2 || 444 || 9000 || 012

non-matches:

9.2 || -90

Is there a particular reason that you're trying to do an arithmetic comparison using regex? You KNOW you're killing a spider with a shotgun, right? — ghoti, Mar 05 '12 at 11:40
No, I'm going to use it for Qty count, I don't want the user to allow 0,-1, 2.3. just positive whole numbers. — Randel Ramirez, Mar 05 '12 at 11:46
randelramirez1, why not just use `if(is_numeric($var) && $var != 0)` ?! — ghoti, Mar 05 '12 at 12:34
@ghoti good thought, but `is_numeric` allows negative numbers, decimals, etc. — Daniel Lubarov, Mar 05 '12 at 12:45
Ah, I mis-read. Then `if(is_numeric($var) && $var > 0)` will do. — ghoti, Mar 05 '12 at 15:28

Prince John Wesley · Answer 1 · 2012-03-06T04:33:43.437

8

^0*[1-9]\d*$ will match all numbers excluding zero.

edited Mar 06 '12 at 04:33

answered Mar 05 '12 at 11:42

Prince John Wesley

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@TimPietzcker, the `*?` is intended to be a "[lazy star](http://en.wikipedia.org/wiki/Regular_expression#Lazy_quantification)" , since `*` by itself is greedy. I don't think it's required (or makes any difference) for something as simple as `0*`, but it's valid notation nonetheless. – ghoti Mar 05 '12 at 15:37
It's valid but completely useless and slower because it leads to a lot of unnecessary backtracking. – Tim Pietzcker Mar 05 '12 at 16:00

Shiplu Mokaddim · Accepted Answer · 2012-03-05T12:07:17.130

6

May be you are looking for ^[1-9]+$ pattern. It'll match 1245, 2253 etc. But not 1003. or 0124. If you want to match the 3rd number (1003) as well use ^[1-9]\d*$ pattern.

In php you'd use

preg_match('/^[1-9]\d*$/', $subject, $matches)

edited Mar 05 '12 at 12:07

answered Mar 05 '12 at 11:40

Shiplu Mokaddim

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Thank you also sir, but I'm getting an error. No ending delimiter '^' in php. How do I fix it. Thank you again sir. – Randel Ramirez Mar 05 '12 at 12:01
1

You didn't specify its [tag:php]. In php use // as delimeter so pattern will be `/^[1-9]\d*$/` – Shiplu Mokaddim Mar 05 '12 at 12:06

score 3 · Answer 3 · answered Mar 05 '12 at 11:37

3

This is obviously:

[1-9]\d*

(one to nine followed by zero or more digits.) This would exclude things like 0190, of course.

answered Mar 05 '12 at 11:37

Ingo

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score 2 · Answer 4 · answered Mar 05 '12 at 12:40

2

I know you asked for a regex, but you might consider

$opts = array(
    'options' => array(
        'min_range' => 1,
        'max_range' => PHP_INT_MAX
    )
);
$n = filter_var($input, FILTER_VALIDATE_INT, $opts);

answered Mar 05 '12 at 12:40

Daniel Lubarov

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score 1 · Answer 5 · answered Mar 05 '12 at 11:51

1

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

this pattern may help you, but i think you must your programming language skills to do arithmetic check. for example in php . "$is_positive = $input > 0" yes it is so easy :)

answered Mar 05 '12 at 11:51

Tufan Barış Yıldırım

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thank you sir. yes, I just wanted to use regular expression to validate the user input for before I send the values to the database. Thank again sir. – Randel Ramirez Mar 05 '12 at 11:57

Naveen Kumar · Answer 6 · 2012-03-05T12:40:04.683

1

Try this

[1-9]\d*|[0]*[1-9]\d*

edited Mar 05 '12 at 12:40

answered Mar 05 '12 at 12:25

Naveen Kumar

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score 0 · Answer 7 · answered Oct 09 '13 at 23:27

0

Here's one that allows 0 up to 100 but not 01

^((([0]$)|[1-9][0-9]{0,1})|100)$

answered Oct 09 '13 at 23:27

Agrapha

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What's the regular expression for positive whole numbers only? (zero is not allowed)

7 Answers7

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