________________________________
From: tedd <tedd.sperling@xxxxxxxxx>
To: php-general@xxxxxxxxxxxxx; ash@xxxxxxxxxxxxxxxxxxxx; Daevid Vincent <daevid@xxxxxxxxxx>
Sent: Wed, October 7, 2009 12:42:41 PM
Subject: RE: 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 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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