PHP regex: how to store $1, $2 in a variable - php

Question

preg_replace('/([a-z]+)([0-9]+)/', '$2$1', $str);
I want to store $1 and $2 in a variable. How can I store it in a variable?

Answer 1

Finding matches is the job of preg_match().
preg_match('/([a-z]+)([0-9]+)/', $str, $matches);
matches:
If matches is provided, then it is filled with the results of search. $matches[0] will contain the text that matched the full
pattern, $matches[1] will have the text that matched the first
captured parenthesized subpattern, and so on.
$full_pattern = $matches[0]
$a = $matches[1] // $1
$b = $matches[2] // $2
$c = $matches[3] // $3
$n = $matches[n] // $n

Answer 2

Use preg_replace_callback:
$one; $two;
function callback($matches)
{
global $one,$two;
$one = $matches[0];
$two = $matches[1];
return $matches[1].$matches[0];
}
preg_replace_callback('/([a-z]+)([0-9]+)/', 'callback', $str);
NOTE
Global is... not a good idea. I actually left that in because it is a concise, clear example of how to accomplish what you're trying to do. I would that I had never used the word, but global is there now and I don't feel right removing it. Actually, its existence saddens me deeply. You are far better off with something like this:
class Replacer
{
private $matches, $pattern, $callback;
public function __construct($pattern, $callback)
{
$this->pattern = $pattern;
$this->callback = $callback;
}
public function getPregCallback()
{
return array( $this, '_callback' );
}
public function _callback( array $matches )
{
$template = $this->pattern;
foreach( $matches as $key => $val )
{
if( $this->callback )
{
$matches[ $key ] = $val = $this->callback( $val );
}
$template = str_replace( '$' . ( $key + 1 ), $val, $template );
}
$this->matches = $matches;
return $template;
}
public function getMatches(){ return $this->matches; }
}
USE
// does what the first example did, plus it calls strtolower on all
// of the elements.
$r = new Replacer( '$2$1', 'strtolower' );
preg_replace_callback('/([a-z]+)([0-9]+)/', $r->getPregCallback(), $str);
list( $a, $b ) = $r->getMatches();

Answer 3

Use preg_replace_callback:
preg_replace_callback('/([a-z]+)([0-9]+)/', function($m) {
// save data
return $m[1].$m[0];
}, $str);
(This uses PHP 5.3 anonymous function syntax, on older PHP just define a normal function and pass its name as the second parameter.)

Answer 4

use preg_replace with "e" ( eval flag)
or better use
preg_replace_callback
http://php.net/manual/en/function.preg-replace-callback.php
see code here :
http://codepad.org/22Qh3wRA
<?php
$str = "a9";
preg_replace_callback('/([a-z]+)([0-9]+)/', "callBackFunc", $str);
function callBackFunc($matches)
{
var_dump($matches);
// here you can assign $matches elements to variables.
}
?>