preg_replace with limits

PaPPy

i have a loop going on that goes through some html code that is all the same

i need to do a preg_replace but only on the first value it finds, not any others

i know there is a limit option but every example i have tried, fails

can someone post the code to replace the first instance preg_replace finds?

thank you

PaPPy

does anyone know a way to get this to work as i really need it fixed

jheitz

Does setting the limit in preg_replace to 1 not work for you?

Weedpacket

Whatever gets posted would work according to how it's described in the [man]preg_replace[/man] section of the manual.

Perhaps you'd have more luck if you showed how you're trying to do it and then there'll be some hope that someone will see what your mistake is and show you how you can fix it.

PaPPy

i have seen the example on php.net and i dont understand how it works with the limit
is it a comma after ur varible to replace from?

$result = preg_replace($thrednumb . $result1 . $thrednume, '~', $result, 1);

Weedpacket

yes

jheitz

Try this example:

$Str = "Test: replace first e on text with a d";
$CharTRep = "/e/";
$RepWith = "3";

echo preg_replace("/e/", "d", $Str , 1);

This will output:

Tdst: replace first e on text with a d

As expected. Hope that helped...

PaPPy

jheitz wrote:
Try this example:
$Str = "Test: replace first e on text with a d";
$CharTRep = "/e/";
$RepWith = "3";

echo preg_replace("/e/", "d", $Str , 1);
This will output:

As expected. Hope that helped...

is there a reason u put "/e/" ???

and neither examples work

jheitz

Yes, regular expresions. Search for some samples in the net to find out how to use them...

LoonyLuke

Hi,

I have a simular problem (which might be the same as PaPPy's ? )

I have some HTML which my script is converting to BBCode.

The page recieving the HTML and converting it shall recieve an unlimited, yet unknown, number of image tags ending with:

" alt="" width="xxx" height="xxx" />

The xxx shall be replaced by an unknown number.

If I run:

$message = preg_replace("/\" alt(.*)\/>/", "END_OF_IMAGE", $message, 1);

this works fine for the first image, but if there are multiple images it uses the first alt tag and last />. This means that it does not work with multiple images. Does anyone know a way around this? Maybe I need to somehow do a count of the number of tags starting with <img and use that number as the limit. Would that work?

BTW I then later on replace the ENG_OF_IMAGE with [/img] in the main str_replace

Hope someone can help 🙂

xblue

LoonyLuke, this is due to the natural greediness of regular expression, the will always take as much as they can get 😃

The preg functions can be made to behave ungreedy, either in general or for parts of the pattern. Where possibly, the IMHO better way would be to make the pattern so specific that it cannot happen in the first place. In your case, I'd suggest to replace the . (any character) with [^>] (any character except closing angular bracket) and you should be fine.

LoonyLuke

Cheers Mate 🙂 Works like a dream!