Matching html input values with regex

Question

I am trying to match a string like the following:

<input type="text" value="cbyEOS56RK3lOxtiCrhmWSkDuNWwrFN4" name="iden">

This is my code:

$pattern = '~value="(.+?)" name="iden"~';
preg_match($pattern, $page, $match);
print_r($match);

As you can probably see, I am trying to match the value in this HTML input. By what I know of regular expressions, .* will match as many characters as possible until it satisfies the next token (in this case ").

I have the name="iden" part in my regex because there are other HTML inputs on the page and I only want to match this one.

Problem is, I'm not getting any matches at all. $match is an empty array. And I know that $page has the right content because I can see it when I echo it.

Help fixing my regex is appreciated, thanks.

This regex works fine when I test it. Are you sure that the content $page doesn't have any extra white space that your regex is not accounting for (newlines, tabs, extra spaces between attributes, etc...)? — Ben Lee
– Ben Lee, Commented Oct 25, 2010 at 20:00

eldarerathis · Accepted Answer · 2010-10-25 20:13:17Z

1

Since you used the phrase "there are other inputs on the page", I assume you're trying to parse out this particular tag from a full HTML document. In that case, I recommend using a DOM parser rather than regular expressions (I'm not trying to be facetious with that link, there's just a lot of options so that seemed easiest). They are designed specifically for this purpose and will be a lot easier in the end.

If you want to try regex anyway, I would personally use ([^"]+) instead of (.+?):

$pattern = '~value="([^"]+)" name="iden"~';

Though this still doesn't address whatever is causing your problem, as your regex should match on that line.

edited Oct 25, 2010 at 20:13

answered Oct 25, 2010 at 19:59

eldarerathis

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4 Comments

Ben Lee Over a year ago

I don't fully agree with tihs. Depending on the task, a full-fledged DOM parser might well be overkill. A simple regex is often the best tool for a task like this.

eldarerathis Over a year ago

@Ben Lee: The DOM parser would more elegantly handle the arbitrary whitespace/newlines/etc that you refer to in your previous comment, though. If this was as simple as the question appears initially, then his regex ought to work, no?

Ben Lee Over a year ago

Good point. Agreed that a DOM parser is generally better if you're the whitespace is variable (a regex to account for optional whitespace everywhere can get really ugly).

eldarerathis Over a year ago

@Ben Lee: Yup, that's pretty much all I was getting at. If it really is "I need to match this line" then it should work, so I'm guessing it's something else...

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