Get all numeric before first Alpha in PHP String - php

Question

I'm trying to get all numeric before space/alpha in PHP string.
Example:
<?php
//string
$firstStr = '12 Car';
$secondStr = '412 8all';
$thirdStr = '100Pen';
//result I need
firstStr = 12
SecondStr = 412
thirdStr = 100
How do I can get all the number of a string just like example above?
I've an idea to get the position of first Alpha, then get all numeric before that position.
I've successfully get the position using
preg_match('~[a-z]~i', $value, $match, PREG_OFFSET_CAPTURE);
But I'm not done yet to get the numeric before the posisition.
How do I can do that, or anybody know how to fix my idea?
Anyhelp will be appreciated.

Answer 1

You don't need to use regex for strings like the examples you've shown, or any functions at all for that matter. You can just cast them to ints.
$number = (int) $firstStr; // etc.
The PHP rules for string conversion to number will handle it for you.
However, because of those rules, there are some other types of strings that this won't work for. For example, '-12 Car' or '412e2 8all'.
If you do use a regex, be sure to anchor it to the beginning of the string with ^ or it will match digits anywhere in the string as the other regex answers here do.
preg_match('/^\d+/', $string, $match);
$number = $match[0] ?? '';

Answer 2

Here's an extremely hackish approach that will work in most situations:
$s = "1001BigHairyCamels";
$n = intval($s);
$my_number = str_replace($n, '', $s);

Answer 3

$input = '100Pen';
if (preg_match('~(\d+)[ a-zA-Z]~', $input, $m)) {
echo $m[1];
}

Answer 4

This function will do the job!
<?php
function getInt($str){
preg_match_all('!\d+!', $str, $matches);
return $matches[0][0];
}
$firstStr = '12 Car';
$secondStr = '412 8all';
$thirdStr = '100Pen';
echo 'firstStr = '.getInt($firstStr).'<br>';
echo 'secondStr = '.getInt($secondStr).'<br>';
echo 'thirdStr = '.getInt($thirdStr);
?>