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PHP

Posted by Łukasz Czuliński
Łukasz Czuliński
8,646 Points

Regular Expressions help: preg_match()

I'm starting to learn Regular Expressions and having some issues.

Basically, I'm trying to parse APA references. For example, with:

Qaseem A, et al. (2008). Current pharmacologic treatment of dementia: A clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Annals of Internal Medicine, 148: 370–378.

My current method for extracting the title is:

public static function titleExtract($reference) 
{
    preg_match('/(\)\.).+?\./', $reference, $match);
    return $match[0];
}

But the output is:

). Current pharmacologic treatment of dementia: A clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians.

And I'm trying to get:

Current pharmacologic treatment of dementia: A clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians

I thought by declaring (\)\.) at the beginning and \. at the end, I'm saying, "get everything between those characters, not including them. I've seen a few examples online with similar regexes and the characters in question aren't included in the return. What am I doing wrong?

thomascawthorn
thomascawthorn
22,986 Points

To help you along, try out this If you're not already.

Very simple but nice gui you can copy and paste code into to see instant response!

Łukasz Czuliński
Łukasz Czuliński
8,646 Points

Thanks. Yeah, have been playing around with that. Very useful, but too bad look-behinds aren't supported in JS.

1 Answer

Łukasz Czuliński
Łukasz Czuliński
8,646 Points

Solved it. Not sure if this is the cleanest method, but used a look-ahead and look-behind.

public static function titleExtract($reference) 
{
    preg_match('/(?<=\)\.\s)(.+?)(?=\.\s)/', $reference, $match);
    return $match[0];
}