String compare algorithm

Question

I am trying to write some php code to check if a name is contained in another (boolean method).

I am currently using strpos to determine if str1 is in str2, however i want it to be a little smarter. i.e. only check if the str1 exists by itself and not part of another unrelated name/string.

compareStrings(str1,str2)

e.g.

GAP & THISISNOTAGAP //should return false
GAP & IN THE GAP //should return true
GAP & GAP //shop return true

ROSS & CROSSROADS //should return false
ROSS & ROSS - CHICAGO //should return true

Any ideas if there is a built in function or regex i can use to achieve above? Thanks.

Jacob · Accepted Answer · 2011-03-26 02:26:21Z

4

Aasmund is totally correct. I thought I should expand on how it would be done with PHP.

Using: preg_match() and preg_quote().

Its important to use preg_quote so that words with regular expession characters in them don't mess up the test.

Your example tests are included.

<?php
function wordInString($word, $string) {
    return preg_match('/\b'.preg_quote($word, '/').'\b/', $string);
}

$tests = array(
    array('GAP', 'THISISNOTAGAP', false),
    array('GAP', 'IN THE GAP', true),
    array('GAP', 'GAP', true),

    array('ROSS', 'CROSSROADS', false),
    array('ROSS', 'ROSS - CHICAGO', true),
);

foreach($tests as $test) {
    assert(wordInString($test[0], $test[1]) == $test[2]);
}

answered Mar 26, 2011 at 2:26

Jacob

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Aasmund Eldhuset · Accepted Answer · 2011-03-26 02:15:48Z

3

With regexes, you can use \b to denote a word boundary: \bGAP\b (I hardly know PHP, but I guess you'll have to enter the string literal as "\\bGAP\\b").

answered Mar 26, 2011 at 2:15

Aasmund Eldhuset

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