How to concatenate increment operator to PHP - php

Question

$i = 0;
while ($slider_query->have_posts()) {
$slider_query->the_post();
$html ='<div class= "col-lg-3 order-lg-'.$i.' col-md-6 p-0">';
$html .= '<div class= "ss-pic">';
$html .= '<img src="'.get_the_post_thumbnail_url(get_the_ID(), 'full').'"/>';
$html .='</div>';
$html .='</div>';
$html ='<div class= "col-lg-3 order-lg-"'.++$i.'"col-md-6 p-0">';
$html .= '<div class= "ss-text">';
$html .= '<h3>'.get_the_title().'</h3>';
$html .= get_the_content();
$html .= 'Explore';
$html .='</div>';
$html .='</div>';
I want to pre-increment the $i. Can anyone please help me out? I know its a basic, but I have a bit of confusion over the concatenation

Answer 1

So firstly you can pre-increment an integer variable by prepending ++ to it, e.g.
++$i
. That will work for you, e.g.
'<div class= "col-lg-3 order-lg-'.++$i.' col-md-6 p-0">'
However, you also have another problem which is preventing you from seeing the results as you are expecting. Every time you write $html = - which is twice within your loop, you overwrite the contents of $html. The previous contents of the variable are destroyed. Therefore, at whatever time you come to echo $html to the output, you'll only ever see the last version.
You need to concatenate all the HTML together into a single string without overwriting it.
Put
$html = "";
just before the loop starts, and then change
$html ='<div class= "col-lg-3 order-lg-'.$i.' col-md-6 p-0">';
to
$html .='<div class= "col-lg-3 order-lg-'.++$i.' col-md-6 p-0">';
(note the .= there, and also the ++$i which you forgot)
and lower down, change
$html ='<div class= "col-lg-3 order-lg-"'.++$i.'"col-md-6 p-0">';
to
$html .='<div class= "col-lg-3 order-lg-"'.++$i.'"col-md-6 p-0">';
(again just changing the = to .=.)
Demo: http://sandbox.onlinephpfunctions.com/code/7e1ac7b039867eedd22d90dfcdc03e8990419a8f

Answer 2

$i = 0;
while ($slider_query->have_posts()) {
$slider_query->the_post();
$html ='<div class= "col-lg-3 order-lg-'.$i+1.' col-md-6 p-0">';
$html .= '<div class= "ss-pic">';
$html .= '<img src="'.get_the_post_thumbnail_url(get_the_ID(), 'full').'"/>';
$html .='</div>';
$html .='</div>';
$html ='<div class= "col-lg-3 order-lg-"'.$i+2.'"col-md-6 p-0">';
$html .= '<div class= "ss-text">';
$html .= '<h3>'.get_the_title().'</h3>';
$html .= get_the_content();
$html .= 'Explore';
$html .='</div>';
$html .='</div>';
I dont think you can increase a value in one loop. you need to add it with numeric value since you want a different value for each div in one loop