PHP: wrapping each group of 3 elements - php

Question

I am trying to figure out how to write a loop that will wrap every group of 3 elements. However, for the last iteration, it should wrap whatever is left (be it one, two or three elements)
So basically this kind of pattern:
div
do stuff
do stuff
do stuff
end-div
div
do stuff
do stuff
do stuff
end-div
div
do stuff
do stuff
do stuff
end-div
div
do stuff
end-div
Here is where I'm at so far:
<?php
$counter = 0;
for ($i = 1; $i <= 10; $i++) {
if (($counter + 1) % 3 == 0) {
echo 'div <br />';
}
echo 'do stuff <br />';
if (($counter + 1) % 3 == 0) {
echo 'end-div <br />';
}
$counter ++;
}
?>
This is giving me the following:
do stuff
do stuff
div
do stuff
end-div
do stuff
do stuff
div
do stuff
end-div
do stuff
do stuff
div
do stuff
end-div
do stuff
Can anyone see where I'm going wrong?

Answer 1

In other words, you need to write div before each group of three items and end-div after each group of three items:
// $counter always tells the number of processed items
$counter = 0;
for ($i = 1; $i <= 10; $i++) {
// before a group of three, $counter is a multiple of three
if ($counter % 3 == 0) {
echo 'div <br />';
}
// process the item then count it
echo 'do stuff <br />';
$counter ++;
// after a group of three, $counter is a multiple of three
if ($counter % 3 == 0) {
echo 'end-div <br />';
}
}
// close the last group if it is not complete
if ($counter % 3 != 0) {
echo 'end-div <br />';
}
Check it online.

Answer 2

There's no need to use separate $counter variable, make use of $i variable in the for loop itself.
echo 'div <br />';
for ($i = 0; $i < 10; $i++) {
if($i != 0 && $i % 3 == 0)
echo 'end-div <br /> div <br />';
echo 'do stuff <br />';
}
echo 'end-div';

Answer 3

This is how I solved the problem
$total_items = 11;
for( $i = 0; $i < $total_items; $i ++ ){
// get the starting element
// the starting element will have ($i + 1 ) % 3 = 1
// all starting elements in the group will have a modulus of 1 when divided by 3
if( ( $i + 1 ) % 3 == 1 ){
echo "div <br />";
}
echo "do stuff <br />";
// the group will either end where ($i + 1 ) % 3 = 0
// or at the end of the count
// if total items are 2 then it will end at 2
if( ( $i + 1 ) % 3 == 0 || ( $i + 1 ) == $total_items ){
echo "end-div <br /><br />";
}
}
I ran my code using w3schools PHP compiler, please see the screenshot