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

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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

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