Advanced str_replace()

[sp.Alive]

I was wondering if anyone could help out.
I want to create a script which acts in a way similar to BBcode.
In a user-editable text-box, users would be able to write thinks like:

[link url="http://www.sitepoint.com"]Go To Sitepoint[/link]

I want to change this into the form of:

<a href="http://www.sitepoint.com">Go To Sitepoint</a>

I think PHP's str_replace() function would be the correct method, but I just can't figure out how I would use is.
I know that I could just use BBcode but i would like to be able to make this from scratch, as it needs some unique features.
Any help on how I would do this would be appreciated.

[spikeZ]

preg_replace would be better for this.
Here is a function I use:

function bbcode_format($str) {

        
        $str = htmlentities($str); 

        $simple_search = array(
                                '/\[h1\](.*?)\[\/h1\]/is',
                                '/\[h2\](.*?)\[\/h2\]/is',
                                '/\[h3\](.*?)\[\/h3\]/is',
                                '/\[h4\](.*?)\[\/h4\]/is',
                                '/\[b\](.*?)\[\/b\]/is',                                
                                '/\[i\](.*?)\[\/i\]/is',                                
                                '/\[u\](.*?)\[\/u\]/is',
                                '/\[s\](.*?)\[\/s\]/is',
                                '/\[LINK=(.*?)\](.*?)\[\/LINK]/is',
                                '/\[red\](.*?)\[\/red]/is',
                                '/\[blue\](.*?)\[\/blue]/is',
                                '/\[IMG\](.*?)\[\/IMG\]/is',
                                );

        $simple_replace = array(
                                '<h1>$1</h1>',
                                '<h2>$1</h2>',
                                '<h3>$1</h3>',
                                '<h4>$1</h4>',
                                '<strong>$1</strong>',
                                '<em>$1</em>',
                                '<u>$1</u>',
                                '<s>$1</s>',
                                '<a href="$1">$2</a>',
                                '<span style="color: red">$1</span>',
                                '<span style="color: blue">$1</span>',
                                '<div class="img_border"><img src="'. constant('IMAGE_PATH') .'/thumbs/$1" alt="$1"/></div>',
        
                                );

        // Do simple BBCode's
        $str = preg_replace ($simple_search, $simple_replace, $str);

        return $str;
} 

usage

$txt = "this is [link="http://www.sitepoint.com"]Go To Sitepoint[/link]
echo bbcode_format($txt); 

Try it and see what happens

[sp.Alive]

Thats great, and it worked fine. Thanks!
Do you think you could explain the elements inside the arrays in the function? That would help me a lot. I get how it works, im just unsure of what some of the values in the arrays mean.
Thanks again.

[spikeZ]

Sure

$str = htmlentities($str); 

http://www.php.net/htmlentites
(saves me saying it!)

What you then have are 2 arrays; the first holds the pattern for replacement and the second is the pattern to search for.

So to take the H1 as an example

'/\[h1\](.*?)\[\/h1\]/is', 

/ open the pattern
\ escapes the first [
h1 is then obviously the tag
\ escapes the second ]
(.*?) is an ATOM and basically a greedy one. It says match anything between the [h1]..[/h1] tags
\[ escapes the [
\/ escapes the /
h1 other tag
\] escapes ]
/ closes the pattern
i case insensitive search
s any whitespace character

This then stores the matches it finds in the $1 variable ($1 because there is one atom)

the replacement '<h1>$1</h1>' takes the contents of $1 and puts it between the <h1></h1> tags.

HTH and welcome to the forums

[UFTimmy]

S
(.*?) is an ATOM and basically a greedy one. It says match anything between the [h1]..[/h1] tags

Just as a point of clarification, this is NOT a greedy regex. The ? at the end specifically tells it not to be greedy.

[spikeZ]

good spot UFTimmy

[sp.Alive]

Sure

$str = htmlentities($str); 

http://www.php.net/htmlentites
(saves me saying it!)

What you then have are 2 arrays; the first holds the pattern for replacement and the second is the pattern to search for.

So to take the H1 as an example

'/\[h1\](.*?)\[\/h1\]/is', 

/ open the pattern
\ escapes the first [
h1 is then obviously the tag
\ escapes the second ]
(.*?) is an ATOM and basically a greedy one. It says match anything between the [h1]..[/h1] tags
\[ escapes the [
\/ escapes the /
h1 other tag
\] escapes ]
/ closes the pattern
i case insensitive search
s any whitespace character

This then stores the matches it finds in the $1 variable ($1 because there is one atom)

the replacement '<h1>$1</h1>' takes the contents of $1 and puts it between the <h1></h1> tags.

HTH and welcome to the forums

Really, really useful! Thanks, that cleared up a lot. If this forum had reputation or something (which it should) you would be getting some. Thanks again.

[spikeZ]

no problem, glad I could help