CODEWITHSUNDEEP
phpregexpreg-match-all
OnIIcE
OnIIcE

Reputation: 871

preg_match_all spaces with fullstops regex

I am writing some unit tests for some methods I am using, and have found a weird bug and would like some Regex advice.

when doing:-

$needle = ' ';
$haystack = 'hello world. this is a unit test.';
$pattern = '/\b' . $needle . '\b/';
preg_match_all($pattern, $haystack, $matches, PREG_OFFSET_CAPTURE, $offset)

I'm expecting the positions to positions found to be 

[5, 12, 17, 20, 22, 27]

The same as if I did this, to get none exact whole word matches

while (($pos = strpos($haystack, $needle, $offset)) !== false) {
   $offset = $pos + 1;
   $positions[] = $pos;
}

However the preg_match_all does not find the 2nd occurrence (12) the space between 

. this

Is this to do with the \b boundary flag? How can I resolve this to make sure it picks up other this?

Thanks

Upvotes: 1

Views: 47

Answers (1)

Death-is-the-real-truth
Death-is-the-real-truth

Reputation: 72289

You have to change your $pattern in preg_match_all() like below:-

<?php
$haystack = 'hello world. this is a unit test.';
while (($pos = strpos($haystack, ' ', $offset)) !== false) {
   $offset = $pos + 1;
   $positions[] = $pos;
}

echo "<pre/>";print_r($positions);

preg_match_all('/\s/', $haystack, $matches,PREG_OFFSET_CAPTURE);

echo "<pre/>";print_r($matches);

Output:- https://eval.in/725574

Note:- you need to use \s for checking white-spaces

You can apply an if-else to change $pattern based on $needle:-

if($needle == ''){
   $pattern = '/\s/';
}else{
   $pattern = '/\b' . $needle . '\b/';
}

Upvotes: 1

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