PHP: find biggest overlap between multiple strings - php

Question

I have this array:
$array = array('abc123', 'ac123', 'tbc123', '1ac123');
I want to compare each string to each other and find the longest common substring. In the example above the result would be c123.

Answer 1

Update
I've completely misunderstood the question; the aim was to find the biggest overlap between an array of strings:
$array = array('abc123', 'ac123', 'tbc123', '1ac123');
function overlap($a, $b)
{
if (!strlen($b)) {
return '';
}
if (strpos($a, $b) !== false) {
return $b;
}
$left = overlap($a, substr($b, 1));
$right = overlap($a, substr($b, 0, -1));
return strlen($left) > strlen($right) ? $left : $right;
}
$biggest = null;
foreach ($array as $item) {
if ($biggest === null) {
$biggest = $item;
}
if (($biggest = overlap($biggest, $item)) === '') {
break;
}
}
echo "Biggest match = $biggest\n";
I'm not great at recursion, but I believe this should work ;-)
Old answer
I would probably use preg_grep() for that; it returns an array with the matches it found based on your search string:
$matches = preg_grep('/' . preg_quote($find, '/') . '/', $array);
Alternatively, you could use array_filter():
$matches = array_filter($array, function($item) use ($find) {
return strpos($item, $find) !== false;
});
I need to extract the value "c123" like it is the biggest match for all strings in array
I think what you would want to do here is then sort the above output based on string length (i.e. smallest string length first) and then take the first item:
if ($matches) {
usort($matches, function($a, $b) {
return strlen($a) - strlen($b);
});
echo current($matches); // take first one: ac123
}
Let me know if I'm wrong about that.
If you're just after knowing whether $find matches an element exactly:
$matching_keys = array_keys($array, $find, true); // could be empty array
Or:
$matching_key = array_search($find, $array, true); // could be false
Or event:
$have_value = in_array($find, $array, true);

Answer 2

in_array($find, $array);
returns true if it's in the array, but it has to be the exact match, in your case it won't finde 'ac123'.
if you want to see if it contains the string then you need to loop through the array and use a preg_match() or similar

Answer 3

You could use array_filter with a callback.
$output = array_filter ($input, function ($elem) { return false !== strpos ($elem, 'c123'); });

Answer 4

<?php
$array1 = array('abc123', 'ac123', 'tbc123', '1ac123');
if (in_array("c123", $array1)) {
echo "Got c123";
}
?>

Answer 5

You can use in_array as used here http://codepad.org/nOdaajNe
or use can use array_search as used here http://codepad.org/DAC1bVCi
see if it can help you ..
Documentation link : http://php.net/manual/en/function.array-search.php and http://www.php.net/manual/en/function.in-array.php