PHP bug (lambda function with use)

Question

I think I stumbled across a bug in PHP. However, to be sure, I am asking here first.

$k=0;
echo preg_replace_callback('/./', function($groups) use ($k) {
    return $k++;
}, 'xxxxxx');

Script output: 000000

Expected output: 012345

Am I missing something?

ya know .. some people actually read documentation, before they start reporting "bugs". — tereško
– tereško, Commented Feb 13, 2012 at 20:56
I read It, but that is easily overlooked. Such importat thing should be more clearly emphasized. Guess I sould have written "bug" :) — Rok Kralj
– Rok Kralj, Commented Feb 13, 2012 at 21:00

NikiC · Accepted Answer · 2012-02-13 20:55:24Z

8

$k is bound to the closure by value, not by reference. So it will always be the same between multiple closure calls.

You can also pass it by reference using &$k. Note that this will also modify the $k value outside the closure.

answered Feb 13, 2012 at 20:55

NikiC

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2 Comments

Beat me by a minute. A well earned +1.

This explains it well. Thanks.

Madara's Ghost · Accepted Answer · 2012-02-13 20:57:21Z

2

The anonymous function is called every time a match is found, the state of $k is not preserved during (hence, the closure).

Try passing it by reference, or use a global.

answered Feb 13, 2012 at 20:57

Madara's Ghost

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