Simple php logic - php

Question

So I haven't programmed in a while, but i decided to tackle a small web app to get back in the game. Im having a bit of trouble though, and its kind of annoying because I know the answer is simple. So i'm making a databaseless image gallery, and i'm using Twitter Bootstrap as the front end. I want to display the images that i'm reading from a directory using the classic bootstrap row setup like this:
<div class="row">
<div class="col-md-3 portfolio-item">
<img class="img-responsive" src="http://placehold.it/750x450">
</div>
<div class="col-md-3 portfolio-item">
<img class="img-responsive" src="http://placehold.it/750x450">
</div>
<div class="col-md-3 portfolio-item">
<img class="img-responsive" src="http://placehold.it/750x450">
</div>
<div class="col-md-3 portfolio-item">
<img class="img-responsive" src="http://placehold.it/750x450">
</div>
</div>
The problem is that I can only put four images into a row so I cant just do something like:
<div class="row">
<?php echo"$img";?>
</div>
How can I echo a
<div class="row">
every four
<?php echo"$img";?>
I feel like a nested loop may work, but i just cant seem to get it.
Thanks.

Answer 1

You need a loop with an index; then you can check if the index is divisible by 4:
if ($i % 4 == 0) {
?><div class="row"></div><?php
}
Alternately, you can array_chunk your data, and run a nested loop on the results, outputting the row in the outer loop.

Answer 2

For each row
for($i=0; $i<$num_item; $i++) {
Start a new row before the first item and every 4th item following
if($i % 4 == 0) {
echo '<div class="row">';
}
End a row after the 4th item and every 4th item following
if($i % 4 == 3) {
echo '</div>
}
Full code:
for($i=0; $i<$num_item; $i++) {
if($i % 4 == 0) {
echo '<div class="row">';
}
// Print the item here
if($i % 4 == 3) {
echo '</div>
}
}

Answer 3

When dealing with a lot of html code using the (notice the colon and endif)
<?php for (index; condition; step) : ?>
<h1>HTML STUFF</h1>
<?php endif; ?>
alternative syntax is a bit cleaner than the conventional markup.
I would suggest:
<div class="row">
<?php for($i = 0; $i < $total_pics; $i++): ?>
<div class="col-md-3 portfolio-item">
<img class="img-responsive" src="<?php echo $img_link; ?>">
</div>
<?php if ($i % 4 == 3 && $i < $total_pics): ?>
</div>
<div class="row">
<?php endif;
endfor; ?>
</div>
This allows the new row only to be put in place if there are more pictures to show and after the fourth one only.
This allows the html code to be indented as you want and clean the php code up a bit in the process. This also allows the initial row to be self closing if there are no pictures to show.