From: tedd <tedd.sperl...@gmail.com>
To: php-general@lists.php.net; a...@ashleysheridan.co.uk; Daevid Vincent 
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."
>>     $b = ++$a;
>>means to me "increment $a and take the value of $a and assign to $b."
>Which is exactly the reason for the two operators in C.


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.


$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 

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++)


    for($i=1; $i<=10; ++$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.



Tommy>> Why would expect to print 2-10?  The way I read the for loop is:  start 
$i with 1, do loop body until $i <= 10, increment $i  before next loop.  So 
whether post/pre-increment 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...

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