Dave M G wrote:
PHP List,
In the code below, I want to take the text within $content, and change
every instance of [h3] into <h3>, and every instance of [/h3] into
</h3>. And then do the same for [em], [/em], [strong], and so on.
However, this code does absolutely nothing to the text stored in content:
$tags = array ("h3", "em", "strong", "hr");
$content = preg_replace("[" . $tags . "]", "<" . $tags . ">", $content);
$content = preg_replace("[/" . $tags . "]", "</" . $tags . ">", $content);
Clearly I've either misunderstood the use of preg_replace(), or regular
expressions, or arrays, despite having looked them up in the PHP online
manual.
I also tried str_replace(), but predictably that did not help. As far as
I understand it, it does not accept arrays.
What am I doing wrong in the above code?
And can the two preg_replace() commands be achieved in one line?
Thank you for any advice.
--
Dave M G
First of all, why the hell are you using preg_* functions for this?
You're feeding static content to it, no modifiers *at all* (not even
case-insensitivity). I recommend you go back to str_replace() as that is
what you need. You'd also be wise to read up on arrays and regular
expressions (a lot).
preg_replace() uses regular-expressions. Regular expressions require (in
php) 2 delimiters, one at the start of the expression and one at the
end, followed by optional modifiers/flags. Eg:
/regexpGoesHere/i
this would match "regexpGoesHere" and be case-insensitive.
You don't use delimiters (first problem).
Second problem with your code is that you're assuming that [, ], < and >
are not meta-characters. Unfortunately, [ and ] ARE meta-characters.
This means that when you would pass it "[h3]" it would see that as "any
character which is an 'h' or '3' is a valid candidate for this
expression". You would either need to escape it so it becomes \[h3\]
which would mean "any string looking like '[h3]' is a valid candidate".
Right, well, first let's go and fix the mess you've made of your arrays.
Here's a lesson for you:
Say you have
$array = array('a','b','c');
print($array);
print($array);
What do you expect to see?
a
b
?
Because looking at your code it seems like you're expecting something
very strange. The thing you'll see is:
Array
Array
Your correct version would be to either loop over it using a construct
such as foreach(), while() or the like, OR use the special case of
preg_replace and str_replace functions, which may also take 2 arrays as
their parameters. Remember though, you CAN NOT MIX ARRAYS WITH STRINGS
just like that.
So, a more correct version for you would be (using str_replace because
i's faster and easier and more appropriate):
$tagsOld = array ("[h3]", "[em]", "[strong]", "[hr]","[/h3]", "[/em]",
"[/strong]", "[/hr]");
$tagsNew = array ("<h3>", "<em>", "<strong>", "<hr>","</h3>", "</em>",
"</strong>", "</hr>");
$content = str_replace($tagsOld, $tagsNew, $content);
What I've done here is made an array with what is to be replaced and a
second one with what it is to be replaced with. Internally, str_replace
goes over the whole list of $tagsOld and replaces each value with the
corresponding value from $tagsNew (based on position in the array,
meansing the 2nd value from $tagsOld will be replaced with the 2nd value
from $tagsNew).
hope you understand what you did (wrong) now,
- tul
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