Re: Whacky increment/assignment logic with $foo++ vs ++$foo

On Wed, 2009-10-07 at 13:24 -0700, Tommy Pham wrote: > > > ________________________________ > From: tedd <tedd.sperling@gmail.com> > To: php-general@lists.php.net; ash@ashleysheridan.co.uk; Daevid Vincent > <daevid@daevid.com> > Sent: Wed, October 7, 2009 12:42:41 PM > Subject: RE: [PHP] Whacky increment/assignment logic with $foo++ vs ++$foo > > At 1:59 PM +0100 10/7/09, Ashley Sheridan wrote: > >>On Wed, 2009-10-07 at 08:54 -0400, tedd wrote: > >>At 6:15 PM -0700 10/6/09, Daevid Vincent wrote: > >>>Except that: > >>> > >>>$a = 123; > >>>$b = $a++; > >>>echo $b; //gives 123, not 124 > >>> > >>>as you logically expect it to and common sense would dictate, regardless of > >>>what K&R or anyone else says. > >> > >>That's not the way I look at it. > >> > >> $b = $a++; > >> > >>means to me "take the value of $a and assign to $b and then increment $a." > >> > >>Whereas: > >> > >> $b = ++$a; > >> > >>means to me "increment $a and take the value of $a and assign to $b." > >> > >>Cheers, > >> > >>tedd > >> > >> > > > >Which is exactly the reason for the two operators in C. > > > >Thanks, > >Ash > > Ash: > > The reason was simply to provide a different way of doing something. > For example, take the statements of: > > $a = 10; > $b = a$++; // $b = 10 and $a = 11 > > This post-increment operator was a way to assign 10 to $b and > increment $a in one statement. > > Whereas: > > $a = 10; > $b = ++a$; // $b = 11 and $a = 11 > > This pre-increment operator was a way to increment $a and also assign > that value to $b. > > Both are perfectly valid ways of using the operator. Also realize > that the pre-decrement and post-decrement operators worked in similar > fashion. > > Now why would someone want to do that? There could be many reasons, > but that was left to the programmer to use as he/she needed. > > However, what I find wacky about all of this is: > > for($i=1; $i<=10; $i++) > { > echo($i); > } > > and > > for($i=1; $i<=10; ++$i) > { > echo($i); > } > > > Do exactly the same thing. I would have expected the first to print > 1-10, while the second to print 2-10, but they both print 1-10. > > Cheers, > > tedd > > > Tommy>> Why would expect to print 2-10? The way I read the for loop is: start $i with > Tommy>> 1, do loop body until $i <= 10, increment $i before next loop. So whether post/pre-increment > Tommy>> doesn't matter logically. Moreover, your loop can also be written as: > > for ($i=1; $i <= 10;) > { > echo ($i++); > } > > PS: I hate to send reply in 'rich text' but Yahoo's plain text screw up the > quote... I think it's time to switch over to gmail... > > > -- > ------- > http://sperling.com ”U‘+Xš ‰¬À > ³>º1http://ancientstones.com http://earthstones.com > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php That what I thought I said when I said "Which is exactly the reason for the two operators in C." Thanks, Ash http://www.ashleysheridan.co.uk