PHP short circuit lazy evaluation, where is it in the php.net manual?

Question

Sorry if this sounds like a really silly question.

But I Googled the web and also Googled specifically both the php.net site and the stackoverflow.com site. I know PHP does short circuit lazy evaluation when using and, or, &&, || operators, but where is it stated loud and clear in the PHP manual???

I found only Wikipedia as the only 'trusted' source that say PHP does lazy evaluation on these operators.

Fulcrum

I don't know where it's written either, but it's taken for granted a good number of times, for instance when people call like mysql_connect(...) || die("Connection failed");. – Arabel

The most trustworthy source is the source code itself. And as far as I remember from the last time I read it, it's true. – Stellular

Does it matter that it's said to be official or not? It's the way PHP works, code with that idea in mind. – Isodimorphism

Hugh, my question wasn't that silly since someone placed a +1 vote. – Fulcrum

+1: It's a very reasonable concern. It's certainly possible to program without a clear spec, relying on inferences from code examples, hearsay about the intentions of the designers, and poking around the details of the current implementation. But anyone who has to work like that is entitled to worry that their house is built on sand. – Laconic

Wow. This explains so many inexplicable cases where I've had to nest conditionals instead of putting them all in one test. – Boxing

Answer 1

Closest thing I can find to an 'official' mention of PHP's short-circuit implementation: http://php.net/manual/en/language.operators.logical.php

Lolalolande

It's written inside the code snippet. First comment: // foo() will never get called as those operators are short-circuit – Arabel

Thanks for the help!!! It's not stated loud and clear, but it's written there and also with clear examples. – Fulcrum

How about short-circuiting for ?:? Come on, PHP, look at Java. – Crowned

Answer 2

This is not an uncommon feature of expression evaluation. The PHP manual page on logical operators makes a passing reference to it in one of the illustrative examples though.

Short circuit evaluation is a commonly exploited idiom, and you can rely on its continued support in the language, otherwise vast amounts of code would break!

Kentledge