Regular Expressions

robertaccettura

I've got a little question for anyone with some experience with regular expressions in PHP:

I need to return true only if the line contains just an HTML tag, hence:

<hr>

Will Trigger

<br><br>

Will Trigger

AND...

<b>A second paragraph</b>

Would not

Nor would

<p>Test

Secondly Is there a way to use htmlspecialchars() on a string, but so that it only encodes '>' or '<' if it's not html? Hence

5 > 4

is encoded, but

<b>5</b> 4

is not?

Any help?

I can't seem to get my arms around this stuff.

gammaster

Maybe this isnt what you are asking for, because it isnt regex, but it will find lines that only contains tags.

function isJustTags($line) {
    return trim(strip_tags($line)) == '';
    }

Your second question:
use < and > in the first place or handle the output before you put it inside tags.

mflanagan

I'm not the regexp guru, but you might try:

"/^{(<[^>]+>)+$/"}

(I don't know why, but my preview is showing a space before the closing paren; that shouldn't be there; it isn't there in my original.)

I haven't tried this myself, but I think it says to find a pattern which matches the entire string (the '^' and the '$'), consisting of a repetition ("(...)+") of one or more patterns, each pattern containing a "<" followed by any sequence of one or more characters (other than >), up to a ">". It would match:

as well as:

< >

It should not match:

A second paragraph

If you need only alpha, numbers, space, and '/' inside the tag (as in ), then mod the regexp to:

"/^(<[A-Ba-b0-9 \/]+>)+$/"

(There should be a space after the '9', but there should not be a space before the closing paren.)

If you need to get really precise, and ensure that the tag name starts with a char, includes quotation marks, etc., you can mod that appropriately.

robertaccettura

Interesting.

regexp is a bit beyond me still (i'm learning slowly)... I'll give it a try.

Thanks.