With the popularity of APIs that connect to Twitter, Facebook, and even sites like StumbleUpon, it’s becoming increasing important to work with String Handling functions.

Here’s a very handy function to replace a link in a String with the html format for posting on the web.

I can’t remember where I got this from but someone deserves credit for helping write this:

 PHP | 
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function clickable_link($text)
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{
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 $text = preg_replace('#(script|about|applet|activex|chrome):#is', ":", $text);
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 // pad it with a space so we can match things at the start of the 1st line.
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 $ret = ' ' . $text;
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 // matches an "xxxx://yyyy" URL at the start of a line, or after a space.
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 // xxxx can only be alpha characters.
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 // yyyy is anything up to the first space, newline, comma, double quote or <
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 $ret = preg_replace("#(^|[\n ])([\w]+?://[\w\#$%&~/.\-;:=,?@\[\]+]*)#is", "<a href="\" target="\"_blank\""></a>", $ret);
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 // matches a "www|ftp.xxxx.yyyy[/zzzz]" kinda lazy URL thing
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 // Must contain at least 2 dots. xxxx contains either alphanum, or "-"
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 // zzzz is optional.. will contain everything up to the first space, newline,
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 // comma, double quote or <.
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 $ret = preg_replace("#(^|[\n ])((www|ftp)\.[\w\#$%&~/.\-;:=,?@\[\]+]*)#is", "<a href="\" target="\"_blank\""></a>", $ret);
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 // matches an email@domain type address at the start of a line, or after a space.
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 // Note: Only the followed chars are valid; alphanums, "-", "_" and or ".".
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 $ret = preg_replace("#(^|[\n ])([a-z0-9&\-_.]+?)@([\w\-]+\.([\w\-\.]+\.)*[\w]+)#i", "<a href="\">@</a>", $ret);
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 // Remove our padding..
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 $ret = substr($ret, 1);
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 return $ret;
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}
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