Question

I am looking for help to write an efficient PHP algorithm to help me find occurances of a String within another string. Here is currently the situation.

I have two arrays. The first array is the array with text that needs searched (haystack). The second array is an array of terms ot find (needle).

I know that my first array has at least one of my terms from the needles. So, the algorithm needs to say ‘is array2[0] found inside array1[0]? if not, loop, is array2[1] found inside array1[0], etc’ If it is found, exit, advance array1[1] pointer and repeat the process.

I want to make sure this is efficient as I have 10s of 1000s of entries to pricess, and my needle array has 1100 individual needles.

Answer 1

Ok, let’s start with this algorithm, it might not be the fastest but the result is what you want. (Keep loping UNTIL you found the first match)

<?php
for ($i = 0; $i < 1000; $i++) {
    $haystack[] = "Lorem ipsum dolor";
    $needle[] = "no match";
}
// $haystack = array("Lorem ipsum dolor", "Quisque placerat", "Cras quis porttitor orci");
//$needle = array("quis", "Lorem");
$timestamp1 = time() +  microtime();
foreach ($haystack as $word){
    foreach ($needle as $pattern){
        if(strpos($word, $pattern) === false){
            //Keep looping
        }else{
            //exit inner loop
            print "'".$pattern."' is in '".$word."'<br />";
            break;
        }
    }
}

$timestamp2 = time() + microtime();
print "It took me ".($timestamp2 - $timestamp1)." seconds to realize there was no match";

?>

//EDIT: I commented the hard coded array, creating it now dynamically an added a timer.
It takes about 1 second max, if there is no match.