Modulus

[russmichell]

Hi everyone:

Can somebody please explain to me in English, what the '%' (Modulo) operator does and how it does it.

All I wish to do is to place an XHTML <br /> in my image display so that 3 images are displayed per line of the total DB result set.

Here is the code:

$numrows = mysql_num_rows($result);
//loop thru DB content:
$count = 0;
while($row=mysql_fetch_assoc($result))
{
$count++;
//loop thru 3 times before dropping-in new
extract($row);
echo $count;
//Ensure only 3 images displayed per line:
if($count == ($numrows % 3))//<--problem is here - I have NO idea what '%' is doing!!
{
//display 3 images and insert <br />
}
else
{
//display images as is (and/or remainder)

Thanks muchly to anyone who can help me out!
Russ

[Anon]

It simply means "remainder".
So
if($count == ($numrows % 3))
means $count has the value of the remainder from $numrows divided by 3. If there is no remainder then $count is false and the IF statement does not fire of.

[russmichell]

Martin:

Cheers for that, but you'd still be entitled to call me dumbass as I still don't get it!

All I want to do in the loop is:
"for each 3 images echo '<br />' and display next 3 images and so on."

Something like this:

//Ensure only 3 images displayed per line:
if($count == ($numrows % 3))
{
$contentMain .= "$img<br />";
}
else
{
$contentMain .= $img;
}

Cheers a lot.
Russ

[Anon]

0%3 = 0, because 0 = 03+0
1%3 = 1, because 1 = 03+1
2%3 = 2, because 2 = 03+2
3%3 = 0, because 3 = 13+0
4%3 = 1, because 4 = 13+1
5%3 = 2, because 5 = 13+2
6%3 = 0, because 6 = 23+0
7%3 = 1, because 7 = 23+1
------^{------------------}

Instead of $count==($numrows%3) (which is only going to happen once if $numrows isn't changing - when $count is either 0, 1, or 2), you want

($count%3)==1 (I think it's 1 - the first image you show has $count==1, and you obviously want that to be on a new line, so yeah, you want a new line when $count%3==1.)

Y'know, I wonder why this while($row=mysql_fetch_assoc($result)) idiom is so popular - is it only because it's used in the manual? Is there something crushingly bad about using a for loop? Especially when you already know the number of rows?

for($count=1;$count<=$numrows; ++$count)
{
$row=mysql_fetch_assoc($result);
...
}