Efficient check for array items in a string

Question

I have an array like:

arr = array("*" , "$" , "and" , "or" , "!" ,"/");

and another string like :

string = "this * is very beautiful but $ is more important in life.";

I'm looking the most efficient way with the lowest cost to find the member of the array in this string. Also I need to have an array in result that can show which members exist in the string.

The easiest way is using a for loop but I believe there should be more efficient ways to do this in PHP.

this looks like a template implementation, you could just use str_replace with arrays for the needle and replacement parameters — Orangepill
– Orangepill, Commented Jul 5, 2013 at 4:54

zerkms · Accepted Answer · 2013-07-05 04:57:49Z

3

$arr=array("*" , "$" , "#" , "!");

$r = '~[' . preg_quote(implode('', $arr)) . ']~';

$str = "this * is very beautiful but $ is more important in life.";

preg_match_all($r, $str, $matches);

echo 'The following chars were found: ' . implode(', ', $matches[0]);

answered Jul 5, 2013 at 4:57

zerkms

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2 Comments

Amir Sa Over a year ago

Thank you, But It's not working if the array members are more than 1 char for example : "or" , "and"

zerkms Over a year ago

@Amir Sa: generate the regex as (and|or|*|$) etc then

David Lin · Accepted Answer · 2013-07-05 05:09:18Z

If you are looking for the most efficient way, the result of the following code is:

preg:1.03257489204

array_intersect:2.62625193596

strpos:0.814728021622

It looks like looping the array and matching using strpos is the most efficient way.

        $arr=array("*" , "$" , "#" , "!");

        $string="this * is very beautiful but $ is more important in life.";



        $time = microtime(true);

        for ($i=0; $i<100000; $i++){

            $r = '~[' . preg_quote(implode('', $arr)) . ']~';

            $str = "this * is very beautiful but $ is more important in life.";

            preg_match_all($r, $str, $matches);

        }

        echo "preg:". (microtime(true)-$time)."\n";

        $time = microtime(true);

        for ($i=0; $i<100000; $i++){

            $str = str_split($string);

            $out = array_intersect($arr, $str);

        }


        echo "array_intersect:". (microtime(true)-$time)."\n";


        $time = microtime(true);

        for ($i=0; $i<100000; $i++){

            $res = array();
            foreach($arr as $a){
                if(strpos($string, $a) !== false){
                    $res[] = $a;
                }
            }

        }

        echo "strpos:". (microtime(true)-$time)."\n";

Community · Accepted Answer · 2023-11-17 20:19:54Z

0

You can use array_insersect

$string = "this * is very beautiful but $ is more important in life.";
$arr=array("*" , "$" , "#" , "!");

$str = str_split($string);

$out = array_intersect($arr, $str);

print_r($out);

This code will produce the following output

Array ( [0] => * [1] => $ )

edited Nov 17, 2023 at 20:19

CommunityBot

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answered Jul 5, 2013 at 4:56

DevZer0

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