Detect the first and last post in Wordpress loop

Detect the first and last post in the WordPress loop

if ( $wp_query->post_count == 0 ) {
  // First post
}

if( ( $wp_query->current_post +1) == $wp_query->post_count ) {
  // Last post
}

// detect first, even in paginated results
if( $wp_query->post_count == 0 && !is_paged() ) {
  // First post
}