WordPress 在文章中自動安插廣告碼

wp_insert_adcode_to_post.php

<?php
//functions.php
function mxp_insert_adcode_in_post($content) {
	global $wp_current_filter;
	$support_post_types = array("post");
	if (!in_array(get_post_type(get_the_ID()),$support_post_types) || is_page() || is_feed() || is_archive() || is_home() || in_array('get_the_excerpt', (array) $wp_current_filter) || 'the_excerpt' == current_filter()) {
		return $content;
	}

	$adcode_for_post_center01 = '<p><div id="mxp_ad_post_center01" style="text-align: center;">廣告碼01</div></p>';
	$adcode_for_post_center02 = '<p><div id="mxp_ad_post_center02" style="text-align: center;">廣告碼02</div></p>';
	$adcode_for_post_center03 = '<p><div id="mxp_ad_post_center03" style="text-align: center;">廣告碼03</div></p>';
	$findme = '</p>';
	$positions = array();
	$pos = -1;
	while (($pos = strpos($content, $findme, $pos + 1)) !== false) {
		$content = substr_replace($content, '[mxp_ad_code_block]', $pos + strlen($findme), 0);
	}
	$positions = explode("[mxp_ad_code_block]", $content);
	//每幾段安插一段廣告
	$average = 5;
	//亦可以判斷超過某段數後使用平均分散方式
	$threshold = 11;
	if (count($positions) > $threshold) {
		$average = floor(count($positions) / 3);
	}
	$content_with_ad = "";
	for ($i = 0; $i < count($positions); ++$i) {
		if ($i == 0) {
			$content_with_ad .= $positions[$i] . $adcode_for_post_center01;
			continue;
		}
		if ($i == $average) {
			$content_with_ad .= $positions[$i] . $adcode_for_post_center02;
			continue;
		}
		if ($i == ($average * 2)) {
			$content_with_ad .= $positions[$i] . $adcode_for_post_center03;
			continue;
		}
		$content_with_ad .= $positions[$i];
	}
	return $content_with_ad;
}
add_filter('the_content', 'mxp_insert_adcode_in_post');