php_match_all() explanation makes no sense to me

ppowell

http://us4.php.net/manual/en/function.preg-match-all.php

I went here to the PHP manual to look up preg_match_all() and, I'm sorry, but it makes absolutely no sense to me. I don't understand anything anyone said anywhere! It might as well have been written in Hungarian!

My task is simple: I want to read from $contents all occurrence of

^{([a-zA-Z0-9-.]+/)+[a-zA-Z0-9-.]+$}

And place each pattern occurrence into an enumerated array. I believe preg_match_all() does that but I don't understand how it works, and please don't tell me to read the manual, as I said, I don't understand the manual so I need someone to break it down to 3rd grade level for me.

Thanks
Phil

Weedpacket

Unless you're using the /m modifier, there would only ever be one occurrence of that pattern in any string: ^ and $ tie the expression to the beginning and end of the string.

preg_match_all() works like preg_match(), except that where preg_match() stops after finding one match, preg_match_all() keeps going from where preg_match() leaves off, and sees if there are any more matches in the string.

ppowell

Ok I know that much of preg_match_all, but that's as far as I can go. I don't understand the constants nor how the 2-dim array is set. Basically, I just plain don't know how to use it.

Phil

Weedpacket

Originally posted by ppowell
Ok I know that much of preg_match_all, but that's as far as I can go. I don't understand the constants nor how the 2-dim array is set. Basically, I just plain don't know how to use it.

Phil

Oh, okay.
Well, if you know how the array is set for preg_match(), you're a third of the way there.

The default arrangement for the two-dimensional array is a list of arrays the same as what preg_match() would give you if you could apply it repeatedly:

[ [1st matched string] [1st paren'd substring in 1st match] [2nd paren'd substring in 1st match] ...]
[ [2nd matched string] [1st paren'd substring in 2nd match] [2nd paren'd substring in 2nd match] ...]
[ [3rd matched string] [1st paren'd substring in 3rd match] [2rd paren'd substring in 3rd match] ...]
...
]

PREG_SET_ORDER gives the transpose of that array

[ [1st matched string] [2nd matched string] [3rd matched string] ...]
[ [1st paren'd substring in 1st match] [1st paren'd substring in 2nd match] [1st paren'd substring in 3rd match] ...]
[ [2rd paren'd substring in 1rd match] [2rd paren'd substring in 2rd match] [2rd paren'd substring in 3rd match] ...]
...
]

PREG_OFFSET_CAPTURE replaces each element in the two-dimensional array with an array, (making it a three-dimensional array), where the 0th element is the same as above, and the 1st element is the position that that substring appears in the original string.

Try playing around with the second example on the [man]preg_match_all[/man] page, setting various combinations of flags, and print_r the resulting $matches array.

ppowell

Ok, the first two I understand (although PREG_SET_ORDER I see a bit more sensical), but PREG_OFFSET_CAPTURE I'm sorry but playing around with it? I still don't understand it, I'm sorry it makes no sense to me 🙁

So basically PREG_SET_ORDER will set each match found in my string to the first row of a 2-dim array?

Phil