CODEWITHSUNDEEP
phpregex
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Reputation: 121

How to use regular expression to find all numbers starting with "$"

I'm dealing with strings that contain non-comma-separated dollar values. For example:

"LOT 2 - $650000"

I need to be able to find the "$650000" and replace it with "$650,000".

The problem is, I'm a complete novice when it comes to regular expressions. I found a post that suggested this for finding numbers:

preg_match_all('!\d+!', $string, $matches);

This does successfully find both the "2" and the "650000" in my string. However, I want to make sure I only get numbers that start with "$", so I only want to get the "$650000".

Can anyone help me adapt the regular expression to get only numbers that start with "$"?

Upvotes: 0

Views: 82

Answers (4)

Adam Winter
Adam Winter

Reputation: 1934

Kevin's answer is better. I went the long way around:

<?php

$dollarString = 'I would like $100000000000 more than I would like $10000000 but that is still better than $1000 and $99 problems.';

echo '<p>dollarString: ';
var_dump($dollarString);
echo '</p>';

function addCommas ($matches){
    $output = [];
    $number = $matches[1];
    $j = 1;
    for($i=strlen($number)-1; $i>=0; $i--){
        array_push($output, $number[$i]);
        if($j%3 == 0 && $i != 0 && $i != strlen($number)-1){array_push($output, ',');}
        $j++;
    }
    array_push($output, '$');
    $output = array_reverse($output);
    return implode($output);
}

$newString = preg_replace_callback('#\$(\d+)#', 'addCommas', $dollarString);

echo '<p>newString: ';
var_dump($newString);
echo '</p>';

?>

Upvotes: 1

Yusuf Alakram
Yusuf Alakram

Reputation: 1

Try the following:

preg_match_all('!\$\d+!', $string, $matches);

This website really helped me understand how to achieve this

Upvotes: 0

Cary Swoveland
Cary Swoveland

Reputation: 110685

You could replace matches of the following regular expression with a comma to both confirm the presence of the dollar sign and to insert commas in the correct locations.

/(?:\$|\G)\d+?\K(?=(?:\d{3})+$)/

Start your engine!

The PCRE engine performs the following operations.

(?:         : begin non-capture group
  \$        : match '$'
  |         : or
  \G        : assert position at the end of the previous match
)           : end non-capture group
\d+?        : match 1+ digits
\K          : reset starting point of match and no longer include
              previously-consumed characters in reported match
(?=         : begin positive lookahead
  (?:\d{3}) : match 3 digits in a non-capture group
  +         : execute non-capture group 1+ times
  $         : match end of string
)           : end positive lookahead

Upvotes: 1

Kevin
Kevin

Reputation: 41875

Just add the dollar sign in your pattern and use preg_replace_callback then combine number_format. Something like this:

$string = preg_replace_callback('~\$(\d+)~', function($matches) {
    return !empty($matches[1]) ? '$' . number_format($matches[1]) : null;
}, $string);

Upvotes: 1

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