ereg_replace

wcl99

Hi !
How can I make use of ereg_replace to replace <a href="http://abc.php">abc</a> to http://abc.php (abc) ??

andreas

ereg_replace("<a href=\"([^{\"]{0,})\">([^{<]{0,})</a>",}} "\1 (\2)", $your_string);

This should work... not tested tho...

Andreas

[deleted]

By learning the basics of regular expressions.
Search the net for some tutorials.

$a="<a href=\"http://abc.php\">abc</a>";
$b=preg_replace("/<a href=\"(.?)\">(.?)<\/a>/","\1 (\2)",$a);
echo "$a\n$b\n";

and the explenation: READ THIS PLEASE so you can learn something
"/<a href=\"(.+)\">(.+)<\/a>/"

WHat does this do?

The outer quote are just string quotes
The outer /'s define where the pattern to match starts and stops.
<a href=
This needs to be matched. if it doesn't exist in the string, there will be not match, no replace.

\"
Escaped quote, tells PHP not to interpret this quote as PHP code, but as a character that must be matched.
(.+)
brackets mean "treat what's in here as a whole, not as seperate items"
the dot means "any character" and the + means "one or more times.
So (.+) means, "this matches a string of a least one character".

The \" and > mean to match the real quote an bracket
then another (.+) to match whatever is between the > and the </a>
and finally a real </a> (with escape chars to make it real)

Then, in the target you back-reference the matches in the pattern.
Everything you put inside brackets (), like the (.+) can be back-referenced.
So when I put

"\1 (\2)"

The \1 is replaced with whatever matched the first set of () in the pattern,
and \2 is replaced with whatever matched the second ().
Note that here, the \ does not mean escape, it does not print a real "\" character.

wcl99

Vincent:
Thank you very much !!!
I still not familiar with regular expression, can you give me another example ?
that is to validate a url wheather it is starting with http:// or not..

[deleted]

That is even easier. in fact, you don't even have to use regexps for that.
But, as your question is to give an example of regexps....

preg_match("/^{http:\/\//i",$string);}

again the pattern is delimited by the slashes and quotes (quotes for PHP, slashes for the pattern)
this time the pattern starts with a ^.
This means "match at the beginning of the string"
Whatever follows must occur at the beginning of the string.
Then follows the http:// With escapes before the slashes, otherwise they would
be interpreted as "pattern delimiters" and the pattern would end here.
And that's it for the pattern itself, so it can be closed with a slash.

This is all good and well, but this will match only http://, not HTTP://
so I ad a lowercase "i" after the second delimiting slash.
This means: "match the whole thing in a case-insensitive way"
That will make "HTTP://" and "HttP://" match too.

Not that this expression will only make sure the string starts with "http://" or "HTTP://".
That is all it does. If your string is only "http://" you will get a match, even thou "http://" is not a valid url.

Anon

Yeah, vincent, I really appreciate on your great help with regular expression !!!
About the valid and invalid url, this is one of the problem... I have search for many webpage for this regular expression, not found... 🙁 can you help me ??

[deleted]

Nope :-)

It's about time you started trying it out for yourself.
I already explained all the items you need to check for a valid URL.

Start by writing down, in your own words, what a string must contain to be a valid URL.
For example, it must begin with "http://" .. now, what else?

Anon

I tried doing this in reverse to get rid of everything but links but I get garbage back.

I bring in an html page with links in it.
$document = join ('', file ('http://www.php.net'));

Then, if it doesn't contain the string I'm looking for, I try to replace it with "". This displays garbage output.

$text = preg_replace ("/[^<a href=\".?\">.?<\/a>]/", "", $document);

Am I doing this the wrong way if I want to parse an html page to get the links and the descriptions of the links?

Thanks, Doug