[PHP] Re: preg_replace_callback

[Al]

tJey wrote:
Hi. I have problem with preg_replace_callback. It seems that my pattern 
is bad, but I can't find any error.


Pattern : \[\s*((\d|\w|_)+)\s*\]
this pattern is intended to find strings like "[field]",
"[ fi12_eld]"...

but every time I get warning message
"Warning: preg_replace_callback(): Delimiter must not be alphanumeric or 
backslash in test.php on line 100"


$pattern= "%\[[\s\w]+\]%";

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[PHP] Re: preg_replace_callback

[CC Zona]

In article <[EMAIL PROTECTED]>,
 [EMAIL PROTECTED] (Rafael Fernandes) wrote:

> First, sorry for my elementary english...
> I need a function made for PHP3 that works like preg_replace_callback...

Before preg_replace_callback() was introduced, preg_replace() used to have 
another an "f" modifier which had similar functionality.  I'm not sure 
whether that modifier was available back in PHP3, but here's the relevant 
quote about "f" from an old set of PCRE Syntax docs:

> F
> If this modifier is set, preg_replace() treats the replacement parameter as a 
> function name that should be called to provide the replacement string. The 
> function is passed an array of matched elements in the subject string. NOTE: 
> this modifier cannot be used along with /e modifier; and only preg_replace() 
> recognizes this modifier.

If I recall correctly (which I may not), an example would look something 
like this:

$output=preg_replace("/(\w+)/f","'***' . strtolower($1) . '***'",$input);

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[PHP] Re: preg_replace_callback()

[Robin Vickery]

[EMAIL PROTECTED] (Richard Lynch) writes:

> A "callback" is when you execute a function, and you provide to it a name of
> *another* function, which it will call on some data in the middle of its
> task.
> 
> It's a very handy way to provide extreme flexibility in functional
> languages.
> 
> For example:
> 
> function my_array_walk($array, $function){
> while (list($k, $v) = each($array)){
> # Here's the magic that implements a 'callback'
> $function($k, $v);
> }
> }
> 
> function your_echo($key, $value){
> echo "$key $value\n";
> }
> 
> $foo = array('a'=>1, 'b'=>2, 'c'=>3);
> 
> my_array_walk($foo, 'your_echo');
> 
> This rather silly example will "walk" the array and call 'your_echo' on each
> key/value pair.
> 
> Dunno exactly how preg_ uses it though...

It calls the callback function for each match, passing it an array.
The matching string is replaced by whatever the callback function returns.

Here's a fairly pointless example of names and email addresses being replaced
by mailto links with a bit of extra processing on their name...

  -robin

mailto:{$match[2]}\";>{$match[1]}";
}

$testString =<<
"Tommy Atkins" <[EMAIL PROTECTED]>
"Davey Jones" <[EMAIL PROTECTED]>
EOS;

$outputString = preg_replace_callback('/"(.+?)"\s*<(.+?)>/', 'mailto', $testString);

print " $outputString ";
?>

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[PHP] Re: preg_replace_callback()

[Richard Lynch]

A "callback" is when you execute a function, and you provide to it a name of
*another* function, which it will call on some data in the middle of its
task.

It's a very handy way to provide extreme flexibility in functional
languages.

For example:

function my_array_walk($array, $function){
while (list($k, $v) = each($array)){
# Here's the magic that implements a 'callback'
$function($k, $v);
}
}

function your_echo($key, $value){
echo "$key $value\n";
}

$foo = array('a'=>1, 'b'=>2, 'c'=>3);

my_array_walk($foo, 'your_echo');

This rather silly example will "walk" the array and call 'your_echo' on each
key/value pair.

Dunno exactly how preg_ uses it though...

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- Original Message -
From: Arash Dejkam <[EMAIL PROTECTED]>
Newsgroups: php.general
To: <[EMAIL PROTECTED]>
Sent: Saturday, September 08, 2001 7:35 PM
Subject: preg_replace_callback()


> Hi,
>
> What is a callback in preg_replace_callback(...) ?
> how can I use it ? can anybody give me an example ?
>
> Thanks,
> Arash
>
>


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