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<?php function x_the_image( $post_id ) { $attachment_ids = array( 1, 2, 3, 4 ); $next_id = -1; foreach ( $attachment_ids as $idx => $attachment_id ) { if ( $attachment_id == $post_id ) { $next_id = $attachment_ids[ ( $idx + 1 ) % count( $attachment_ids ) ]; break; } } return $next_id; } var_dump( x_the_image(2) === 3, x_the_image(3) === 4, x_the_image(4) === 1, x_the_image(5) );
Output for 4.3.1 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.31, 7.4.0 - 7.4.25, 8.0.0 - 8.0.12, 8.1rc1 - rc3
bool(true) bool(true) bool(true) int(-1)

preferences:
68.42 ms | 537 KiB | 17 Q