Searching within an array of strings

Question

Ok, I'm feeling retarded here,

I have a string like so:

$string = 'function module_testing() {';

or it could be like this:

$string = 'function module_testing()';

or it could be like this:

$string = 'function module_testing($params) {';

or this:

$string = 'function module_testing($params, $another = array())';

and many more ways...

And than I have an array of strings like so:

$string_array = array('module_testing', 'another_function', 'and_another_function');

Now, is there some sort of preg_match that I can do to test if any of the $string_array values are found within the $string string at any given position? So in this situation, there would be a match. Or is there a better way to do this?

I can't use in_array since it's not an exact match, and I'd rather not do a foreach loop on it if I can help it, since it's already in a while loop.

Thanks :)

cletus · Accepted Answer · 2010-05-02 05:32:07Z

2

A foreach loop here is the appropriate solution. Not only is it the most readable but you're looping over three values. The fact that happens within a while loop is a non-issue.

foreach ($string_array as $v) {
  if (strpos($string, $v) !== false) {
    // found
  }
}

You can alternatively use a regular expression:

$search = '\Q' . implode('\E|\Q', $string_array) . '\E';
if (preg_match('!$search!`, $string)) {
  // found
}

There are two parts to this. Firstly, there is the | syntax:

a|b|c

which means find a, b or c. The second part is:

\Q...\E

which escapes the contents. This means if your search strings contain any regex special characters (eg () then the regex will still work correctly.

Ultimately though I can't see this being faster than the foreach loop.

edited May 2, 2010 at 5:32

answered May 2, 2010 at 5:26

cletus

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5 Comments

SoLoGHoST Over a year ago

Well, in this case it's only 3 values, but this is actually not always guaranteed to be the case...

SoLoGHoST Over a year ago

what about stristr, would that be helpful?

cletus Over a year ago

@SoLoG strstr() isn't much different to using strpos() in this case.

SoLoGHoST Over a year ago

Ok, Yeah, I suppose the foreach loop is needed here. Would a for loop be even faster? If I did a count on it first?

cletus Over a year ago

Don't worry about differences between for and while loops. That's micro-optimization and is an irrelevant distraction. Readability is far more important (and any differences are going to be insignificant anyway).

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