Regex to extract block of data

Question

Would somebody care to help me out with a preg_match_all Regex?

I need to extract from a block that looks like this:

(arbitrary data)
alt=BAUSTEIN^550^^transparent^transparent^null^null^(...base64 encoded data...) ^
(arbitrary data)
alt=BAUSTEIN^550^^transparent^transparent^null^null^(...base64 encoded data...) ^

all base64 encoded blocks. The rule is: There is always alt=BAUSTEIN followed by six columns of arbitrary data delimited by ^. The base64 encoded column is also delimited by ^

my current feeble attempt contains a lot of ([^\^].*) and won't match anything. Pointers much appreciated.

Rubens Farias · Accepted Answer · 2010-01-16 23:08:17Z

2

Try this:

alt=BAUSTEIN(?:\^.*?){6}\^(?<base64>.*?)\^

answered Jan 16, 2010 at 23:08

Rubens Farias

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4 Comments

Pekka Over a year ago

Cheers Rubens, I found this regex the most elegant but somehow I couldn't get it to work, I don't know why. The first bracketed expression is beatiful, though, something to keep in mind.

Alix Axel Over a year ago

@Pekka: It's probably the .Net named capture (?<base64>).

Rubens Farias Over a year ago

you're right, @Alix; you can to strip that ?<base64> if you want, but I just read php >= 5.2.2 supports it: php.net/manual/en/function.preg-match-all.php

Pekka Over a year ago

Nope, I stripped the base64 and replaced it by (.*?) (good to know that it's a valid expression though, thanks!) Still doesn't match (the result is empty). Strange, I can't see why.

Alix Axel · Accepted Answer · 2010-01-16 23:37:47Z

1

I don't understand your example very well, but would this do it?

alt=BAUSTEIN\^+(.+?)\^+(.+?)\^+(.+?)\^+(.+?)\^+(.+?)\^+(.+?)\^+

Or a more refined one:

^alt=BAUSTEIN\^+(.+?)\^+(.+?)\^+(.+?)\^+(.+?)\^+(.+?)\^+([0-9a-zA-Z+/=]+)\^+$

answered Jan 16, 2010 at 23:37

Alix Axel

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1 Comment

Alix Axel Over a year ago

No problem, but Ruben solution is much more simpler: alt=BAUSTEIN(?:\^.*?){6}\^(.*?)\^.

ghostdog74 · Accepted Answer · 2010-01-16 23:53:57Z

1

here's one way without regex. since you have distinct delimiters, you can use splitting approach.

$str= <<<A
(arbitrary data)
alt=BAUSTEIN^550^^transparent^transparent^null^null^(...base64 encoded data...) ^
(arbitrary data)
alt=BAUSTEIN^550^^transparent^transparent^null^null^(...base64 encoded data...)
A;

$s = explode("^",$str);
for($i=0;$i<count($s);$i++){
    #check for alt=BAUSTEIN , if yes, go 6 indices forward to get your stuff
    if ( strpos($s[$i] ,"alt=BAUSTEIN" ) !==FALSE){
        print $s[$i+7]."\n";
    }
}

answered Jan 16, 2010 at 23:53

ghostdog74

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1 Comment

Pekka Over a year ago

Cheers Ghostdog, a regex did it for me nicely in this case but this is definitely a valid solution.

streetparade · Accepted Answer · 2010-01-16 23:13:38Z

0

try this

$regex ="@^alt=@BAUSTEIN\^{2}[a-zA-Z]{1}\^[a-zA-Z]{1}\^(.*)"

answered Jan 16, 2010 at 23:13

streetparade

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1 Comment

Rubens Farias Over a year ago

"six columns of arbitrary data"; a 0 in any will break your regex

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