Last post in loop when even

Question

I'm using this code to try and check the last post on each page loop is even so i can add different classes.

This works to check if its the last post :

( ( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count )

This works to check if its a even post

( $wp_query->current_post % 2 == 0 )

But this doesn't check if its the last post and even.

 ( ( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count ) && ( $wp_query->current_post % 2 == 0 );

The problem i have is i want to display posts in columns and avoid the last post displaying in a column with a gap when there's a even amount of posts.

Answer 1

<?php if( have_posts() ) : ?>

    <?php $count = 0; ?>

    <?php while( have_posts() ) : the_post(); ?>

    <?php
    global $count;

    $col = 'col-lg-6';

    if($count%3 == 0) {
        $col = 'col-lg-12';
    } else {
        $col = 'col-lg-6';
    }

    $count++;

    ?>

    <article id="post-<?php the_ID(); ?>" <?php post_class( $col ); ?>>
        [...]
        [...]
        [...]
    </article>

    <?php endwhile; ?>
<?php endif; ?>

Answer 2

In general I think the column layout should be handled with CSS, without the need to change the generated HTML. The number of columns might need to change with device, etc.

So here I just want to look at this statement:

This works to check if its the last post :
( ( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count )

This looks rather complex and would most likely slow down developers trying to evaluate this expression.

Let's drill into this:

The $wp_query->current_post has -1 as initial value, that's incremented for each post in the loop.

The following source references are related to that:

https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/class-wp-query.php#L488

https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/class-wp-query.php#L3069

https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/class-wp-query.php#L3085

https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/class-wp-query.php#L3115

The first post in the loop has $wp_query->current_post as 0. Then this statement becomes:

   ( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count
=> ( 1 == 0 + 1 ) == $wp_query->post_count
=> ( 1 == 1 ) == $wp_query->post_count
=> true == $wp_query->post_count

There are parentheses missing, so we need to check the operator precedence:

https://secure.php.net/manual/en/language.operators.precedence.php

Hopefully I have this correct :-)

The second post in the loop has $wp_query->current_post as 1. Then the statement becomes:

   ( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count
=> ( 1 == 1 + 1 ) == $wp_query->post_count
=> ( 1 == 2 ) == $wp_query->post_count
=> false == $wp_query->post_count

etc

So the check:

( 1 == $wp_query->current_post + 1 ) == $wp_query->post_count

seems to boil down to either:

true == $wp_query->post_count

for the first post in the loop or else

false == $wp_query->post_count

which is probably not what you have in mind.

To check for the last post in the loop, it seems your'e looking for:

current_post(s) | post_count 
----------------------------
 -1                   0
 0*                   1
 0, 1*                2
 0, 1, 2*             3
 0, 1, 2, 3*          4
...

where * marks the last post index in the loop.

The rule to determine the last post in the loop (*), using the current post index and the post count, seems to be:

$wp_query->current_post + 1 === $wp_query->post_count

where $wp_query->post_count > 0.

Also check out the same loop ending condition here:

https://core.trac.wordpress.org/browser/tags/4.9.8/src/wp-includes/class-wp-query.php#L3115

Hope this helps you to investigate this further!