How can I efficiently parse a string for two strings? - php

Question

How can I efficiently determine if a given string contains two strings?
For example, let's say I'm given the string: abc-def-jk-l. This string either contains two strings divided by a -, or it's not a match. The matching possibilities are:
Possible Matches for "abc-def-jk-l" :
abc def-jk-l
abc-def jk-l
abc-def-jk l
Now, here are my columns of strings to match:
Column I Column II
------- -------
1. abc-def A. qwe-rt
2. ghijkl B. yui-op
3. mn-op-qr C. as-df-gh
4. stuvw D. jk-l
How can I efficiently check to see if the given string matches two strings in the columns above? (The above is a match - matching abc-def and jk-l)
Here are some more examples:
abc-def-yui-op [MATCH - Matches 1-B]
abc-def-zxc-v [NO MATCH - Matches 1, but not any in column II.]
stuvw-jk-l [MATCH - Matches 4-D]
mn-op-qr-jk-l [Is this a match?]
Now, given a strings above, how can I efficiently determine matches? (Efficiency will be key, because columns i and ii will each have millions of rows on indexed columns in their respected tables!)
UPDATE: The order will always be column i, then column ii. (or "no match", which could mean it matches only one column or none)
Here's some php to help:
<?php
$arrStrings = array('abc-def-yui-op','abc-def-zxc-v','stuvw-jk-l','stuvw-jk-l');
foreach($arrStrings as $string) {
print_r(stringMatchCheck($string));
}
function stringMatchCheck($string) {
$arrI = array('abc-def','ghijkl','mn-op-qr','stuvw');
$arrII = array('qwe-rt','yui-op','as-df-gh','jk-l');
// magic stackoverflow help goes here!
if ()
return array($match[0],$match[1]);
else
return false;
}
?>

Answer 1

Just use PHP's strpos(). Loop until you find an entry from $arrI in $string using strpos(), and do the same for $arrII.
More info on strpos(): http://php.net/manual/en/function.strpos.php
EDIT:
To help you see what I'm talking about, here's your function:
function stringMatchCheck($string) {
$arrI = array('abc-def','ghijkl','mn-op-qr','stuvw');
$arrII = array('qwe-rt','yui-op','as-df-gh','jk-l');
$match = array(NULL, NULL);
// get match, if any, from first group
for ($i=0; $i<count($arrI) && !is_null($match[0]); $i++) {
if (strpos($string,$arrI[$i]) !== false) {
$match[0]=$arrI[$i];
}
}
if (!is_null($match[0])) {
// get match, if any, from second group group
for ($i=0; $i<count($arrII) && !is_null($match[1]); $i++) {
if (strpos($string,$arrII[$i]) !== false) {
$match[1]=$arrII[$i];
}
}
}
if (!is_null($match[0]) && !is_null($match[1])) {
return $match;
} else {
return false;
}
}

Answer 2

For efficiency sake, rather than loop through every entry in each column, split the string into as many different words as it takes and search for every word combination. Basically what you mention as possible matches.
$words = explode("-", $string);
$end = count($words) - 1;
for ( $i = 1; $i < $end; $i++ ) {
$partOne = array_slice($words, 0, $i);
$parttwo = array_slice($words, $i);
$wordOne = implode("-" , $partOne);
$wordTwo = implode("-" , $partTwo);
/* SQL to select $wordOne and $wordTwo from the tables */
}