If run right now, it will always produce the same value (4), but it isn't *defined* to do so. What that means is that behavior is subject to change without notice, warning, or justification. This is a somewhat harsh way of saying "Don't write expressions with ambiguous evaluations, that's clowny."
I would ask that you don't "fix" the docs, as we want to continue to discourage users from engaging in unsafe behaviors. On Fri, Jul 19, 2013 at 5:12 PM, Yasuo Ohgaki <yohg...@ohgaki.net> wrote: > Hi all, > > Take a look at this bug report. > > https://bugs.php.net/bug.php?id=65087 > > He complains about documentation of ++/--. > The doc says > > http://www.php.net/manual/en/language.operators.precedence.php > --------------- > // mixing ++ and + produces undefined behavior > $a = 1; > echo ++$a + $a++; // may print 4 or 5 > --------------- > > "may print 4 or 5"?? Undefined?? > In old PHP there may be such limitation. > > I cannot believe this is true now, but I ask list before I fix doc. > > Any comments? > > -- > Yasuo Ohgaki > yohg...@ohgaki.net >
