Search for partial string in PHP array? Search value contains hashtag

Question

Example:

$array = array('alpha beta','beta gamma','delta phi', '#alpha phi', 'beta phi');
$searchword = 'alpha';
$results = array_filter($array, function($var) use ($searchword) { return preg_match("/\b$searchword\b/i", $var); });
print_r($results);

Array ( [0] => alpha beta [3] => #alpha phi )

I would like to find only the elements containing #alpha, not alpha.

The result I want is Array ( [3] => #alpha phi ).

However, this doesn't work:

$array = array('alpha beta','beta gamma','delta phi', '#alpha phi', 'beta phi');
$searchword = '#alpha';
$results = array_filter($array, function($var) use ($searchword) { return preg_match("/\b$searchword\b/i", $var); });
print_r($results);

Array ( )

I also tried $searchword = preg_quote('#alpha'); but that doesn't work either. I'm not familiar enough with regex to figure this out-- there must be some regex rule I'm missing out on?

Note: I am not looking to find all the hashtag keywords in the array. I want to search for a specific hashtag keyword.

Credit: I used one of the answers from here: Search for PHP array element containing string

Avinash Raj · Accepted Answer · 2015-07-24T05:09:25.973

2

Remove the starting \b

preg_match("/$searchword\b/i", $var);

or

Use \B

preg_match("/\B$searchword\b/i", $var);

Why?

It's all about word boundaries \b matches between word char and a non-word char or vice-versa. Since the first character is # which is a non-word character and before that character there exists the start of the line boundary. \B is the suitable one for this, which matches between two non-word chars or two word chars. Here start of the line , # so there must exists \B in-between not \b.

edited Jul 24 '15 at 05:09

answered Jul 24 '15 at 05:07

Avinash Raj

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$var is an array - just saying – ArtisticPhoenix Jul 24 '15 at 05:08
@Feanne - you understand that this will match `*alpha`, `+alpha`, `%alpha` as well as the `#alpha` though - just thought I would mention that. Oddly enough only my answer will match `#alpha` exactly and no other starting word. – ArtisticPhoenix Jul 24 '15 at 07:08
@ArtisiticPhoenix his search word is `#alpha`, then how it would match `*alpha` – Avinash Raj Jul 24 '15 at 07:18
sorry I was confusing \B don't see that used much, + its 330am here, my bad – ArtisticPhoenix Jul 24 '15 at 07:30

Jonny 5 · Answer 2 · 2015-07-24T05:42:57.690

2

Drop the first \b word boundary and use $searchword = '#alpha';
To search an array and get entries matching the pattern use preg_grep function:

print_r(preg_grep("/".preg_quote($searchword, "/")."\b/i", $array));

Array ( [3] => #alpha phi )

Test at eval.in

edited Jul 24 '15 at 05:42

answered Jul 24 '15 at 05:11

Jonny 5

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again the lack of the `^` anchor means this will also match `beta #alpha` as well as `b#alpha` etc. – ArtisticPhoenix Jul 24 '15 at 07:12
@ArtisiticPhoenix Question was: ...Search value **contains** hashtag – Jonny 5 Jul 24 '15 at 07:20

score 2 · Answer 3 · answered Jul 24 '15 at 05:13

2

Or you can also use strpos instead of preg_match as

$searchword = '#alpha';
$results = array_filter($array, function($var) use ($searchword) { return (strpos($var,$searchword)>-1); });

answered Jul 24 '15 at 05:13

Narendrasingh Sisodia

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this will match `beta #alpha` as well as `b#alpha` etc. – ArtisticPhoenix Jul 24 '15 at 07:10
Yep that might be the case – Narendrasingh Sisodia Jul 24 '15 at 08:33

ArtisticPhoenix · Answer 4 · 2015-07-24T07:31:13.450

Change your code

 $searchword = 'alpha';

To

$searchword = '^#alpha';

Starts with ^ # hashtag,

 preg_match('/^#alpha/', '#alphasomething');

Will match #alpha

https://regex101.com/r/rU1eA9/1

Doesn't match alpha

https://regex101.com/r/rU1eA9/2

Seeing as this is open to interpenetration

I would like to find only the elements containing #alpha

Some answers may match a variety of things that "contain" #alpha such as b#alphagama or in some cases gamma #alpha etc.

I though I would mention the the leading ^ carrot in my RegX means begins with. So in order for my answer to match the string must begin with a # hashtag followed by alpha literally.

So my answer may not be the best if you are just wanting the "contains" #alpha such as gama#alpha. But if you want begins with #alpha I would recommend using it.

I feel it's important to make sure I high lighted these edge cases, and exactly what the leading ^ means in mine.

Search for partial string in PHP array? Search value contains hashtag

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