How to use PHP preg_replace regular expression to find and replace text?

Question

I wrote this PHP code to make some substitutions:

function cambio($txt){
    $from=array(
        '/\+\>([^\+\>]+)\<\+/', //finds +>text<+
        '/\%([^\%]+)\%/',   //finds %text%
    );

    $to=array(
        '<span class="P">\1</span>',
        '<span>\1</span>',
    );

    return preg_replace($from,$to,$txt);
}

echo cambio('The fruit I most like is: +> %apple% %banna% %orange% <+.');

Resulting into this:

The fruit I most like is: <span class="P"> <span>apple</span> <span>banna</span> <span>orange</span> </span>.

However I needed to identify the fruit's span tags, like this:

The fruit I most like is: <span class="P"> <span class="t1">apple</span> <span class="t2">banana</span> <span class="t3">coco</span> </span>.

I'd buy a fruit to whom discover a regular expression to accomplish this :-)

Whit the Xavier Barbosa's help, I came to this final sollution:

function matches($matches){
    static $pos=0;
    return sprintf('<span class="t%d">%s</span>',++$pos,$matches[1]);
}

function cambio($txt){//Markdown da Atípico : Deve ser usado depois do texto convertido para markdown
    $from=array(
        '/\=>(.+?)<\=/', //finds: =>text<=
        '/\+>(.+?)<\+/', //finds +>text<+
    );

    $to=array(
        '<span class="T">\1</span>',
        '<span class="P">\1</span>',
    );

    $r=preg_replace($from,$to,$txt);
    return preg_replace_callback('/%(.*?)%/','matches',$r);//finds %text%
    //'/%((\w)\w+)%/'   //option
}

the class of the inner span(s) (i.e. class="b") is always equal to the first letter of the fruit ? — Ass3mbler
– Ass3mbler, Commented Jan 13, 2011 at 19:43
Are you writing your own templating language in PHP? Beware of BobX. — Nathan
– Nathan, Commented Jan 13, 2011 at 20:05
Ass3mbler, sorry, I did not intend to make a relation with the content's first letter. I edited the class names to something like: t1, t2 and t3. — Roger
– Roger, Commented Jan 13, 2011 at 21:16
@Roger: No need to edit your question title to say it's solved. The accepted answer will indicate that for you (in most cases) ;) — BoltClock
– BoltClock, Commented Jan 14, 2011 at 0:20

Xavier Barbosa · Accepted Answer · 2011-01-13 23:29:26Z

2

<?php


function cambio($txt){
    $from=array(
        '/\+>(.+?)<\+/', //finds +>text<+
        '/%((\w)\w+)%/',   //finds %text%
    );

    $to=array(
        '<span class="P">\1</span>',
        '<span class="\2">\1</span>',
    );

    return preg_replace($from,$to,$txt);
}

echo cambio('The fruit I most like is: +> %apple% %banna% %orange% <+.');

And a stateful version for PHP5.3

function cambio($txt) {
    return preg_replace_callback('/\+>(.+?)<\+/', function ($matches) {
        $txt = sprintf('<span class="P">%s</span>', $matches[1]);

        return preg_replace_callback('/%(\w+)%/', function ($matches) {
            static $pos = 0;
            return sprintf('<span class="t%d">%s</span>', ++$pos, $matches[1]);
        }, $txt);

    }, $txt);
}

echo  cambio('The fruit I most like is: +> %apple% %banna% %orange% <+.');

edited Jan 13, 2011 at 23:29

answered Jan 13, 2011 at 19:50

Xavier Barbosa

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3 Comments

Roger Over a year ago

Obrigado/Gracias, Xavier! Going a little deeper, is it possible to get this?: The fruit I most like is: apple banna coco .

Xavier Barbosa Over a year ago

Well for this you will need to use the preg_replace_callback()function. But this function is stateless, so you'll need to cheat. See the example, but beware, it works only on PHP5.3

Roger Over a year ago

Perfect! Unretouchable. Thank you.

Klaus Byskov Pedersen · Accepted Answer · 2011-01-13 19:42:23Z

1

Try this:

function cambio($txt){
    $from=array(
        '/\+\>([^\+\>]+)\<\+/', //finds +>text<+
        '/\%(^\%)([^\%]+)\%/',   //finds %text%
    );

    $to=array(
        '<span class="P">\1</span>',
        '<span class="\1">\1\2</span>',
    );

    return preg_replace($from,$to,$txt); }

echo cambio('The fruit I most like is:
+> %apple% %banna% %orange% <+.');

answered Jan 13, 2011 at 19:42

Klaus Byskov Pedersen

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1 Comment

Roger Over a year ago

Well, your code echos: The fruit I most like is: %apple% %banna% %orange% ... Note that I changed a bit what I first wished. I am picturing how I can name the inner span class with a string not related to the content...

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