Agreed.

<?php
// Echo's F and does NOT set $a.
echo (False && ($a=1)) ? 'T' : 'F';

// Echo's T, sets $b but does not set $c.
echo (($b=2) || False || ($c=3)) ? 'T':'F';

// Turn off notices about undefined variables for $a and $c.
error_reporting(E_ALL & ~E_NOTICE);

// Rather than "1 2 3", we get just " 2 ".
echo "$a $b $c";
?>

This isn't a side-effect, but an intrinsic property of these operators. As two out of the four user notes on the page mention, the first dating back to 1999, these operators short-circuit.

Perhaps this could be explained in the text to make it clearer for people new to programming, but I don't think there's any great need;
I assume most people can look up terms they're not familiar with.

Two opposing thoughts.

Delphi - http://info.borland.com/techpubs/delphi/delphi5/oplg/syntlmnt.html#10548
In Delphi, shortcut/short-circuit is optional, though as standard it is enabled.

VB - http://www.informit.com/guides/content.asp?g=dotnet&seqNum=480&rl=1
Seemingly VB does NOT have a short circuit.

Who do you believe. For the seasoned programmer, this is perfectly obvious. But if you're upgrading your skill set from, say, VB, then this REALLY odd behaviour is completely new. And what debugging would you provide?

This should be documented and probably in several places as there are many references to boolean logic throughout the manual.

It is the LACK of documentation on this standard feature within PHP that is the issue.

Good ole MS! http://support.microsoft.com/kb/817250

My point exactly.

A programing language may or may not guarantee side-effects from evaluation of operands to logical operators. Or at least would say
that it is undefined if the side-effect occurs.

The proffesional C++ programmer will find it normal for the language to shortcut the expression, while a beginner will not understand what's wrong with his/her code.

My point was that the term "short-circuit" is already mentioned twice on the page, if you didn't know what it meant in this context then a google search for "short-circuit operator" would yield a page full of relevant results.

Of course it could be spelled out in the text, but even if I was in favour of doing so, I don't have phpdoc karma. That's why I just stated my opinion and left the bug open.

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.