关键的时候能拿得出关键代码才是好的程序员。这篇文章里芒果小站收集了一些诸如此类的关键代码，有用于编程。
如果你的工程项目不是基于 CMS 系统或框架，打造一个简单的缓存系统将会非常实在。下面的代码很简单，但是对小网站而言能切切实实解决问题。
<?php// define the path and name of cached file$cachefile = 'cached-files/'.date('M-d-Y').'.php';// define how long we want to keep the file in seconds. I set mine to 5 hours.$cachetime = 18000;// Check if the cached file is still fresh. If it is, serve it up and exit.if (file_exists($cachefile) && time() - $cachetime < filemtime($cachefile)) {include($cachefile);exit;}// if there is either no file OR the file to too old, render the page and capture the HTML.ob_start();?><html>output all your html here.</html><?php// We're done! Save the cached content to a file$fp = fopen($cachefile, 'w');fwrite($fp, ob_get_contents());fclose($fp);// finally send browser outputob_end_flush();?>点击这里查看详细情况：http://wesbos.com/simple-php-page-caching-technique/
这是一个非常有用的距离计算函数，利用纬度和经度计算从 A 地点到 B 地点的距离。该函数可以返回英里，公里，海里三种单位类型的距离。
function distance($lat1, $lon1, $lat2, $lon2, $unit) { $theta = $lon1 - $lon2;$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));$dist = acos($dist);$dist = rad2deg($dist);$miles = $dist * 60 * 1.1515;$unit = strtoupper($unit);if ($unit == "K") {return ($miles * 1.609344);} else if ($unit == "N") {return ($miles * 0.8684);} else {return $miles;}}使用方法：
echo distance(32.9697, -96.80322, 29.46786, -98.53506, "k")." kilometers";
点击这里查看详细情况：http://www.phpsnippets.info/calculate-distances-in-php
这个有用的函数能将秒数表示的事件转换为年、月、日、小时等时间格式。
function Sec2Time($time){if(is_numeric($time)){$value = array("years" => 0, "days" => 0, "hours" => 0,"minutes" => 0, "seconds" => 0,);if($time >= 31556926){$value["years"] = floor($time/31556926);$time = ($time%31556926);}if($time >= 86400){$value["days"] = floor($time/86400);$time = ($time%86400);}if($time >= 3600){$value["hours"] = floor($time/3600);$time = ($time%3600);}if($time >= 60){$value["minutes"] = floor($time/60);$time = ($time%60);}$value["seconds"] = floor($time);return (array) $value;}else{return (bool) FALSE;}}点击这里查看详细情况：http://ckorp.net/sec2time.php
一些诸如 mp3 类型的文件，通常会在客户端浏览器中直接被播放或使用。如果你希望它们强制被下载，也没问题。可以使用以下代码：
function downloadFile($file){$file_name = $file;$mime = 'application/force-download'; header('Pragma: public'); // required header('Expires: 0'); // no cache header('Cache-Control: must-revalidate, post-check=0, pre-check=0'); header('Cache-Control: private',false); header('Content-Type: '.$mime); header('Content-Disposition: attachment; filename="'.basename($file_name).'"'); header('Content-Transfer-Encoding: binary'); header('Connection: close'); readfile($file_name); // push it out exit();}点击这里查看详细情况：Credit: Alessio Delmonti
想知道今天的天气？这段代码会告诉你，只需 3 行代码。你只需要把其中的 ADDRESS 换成你期望的城市。
$xml = simplexml_load_file('http://www.google.com/ig/api?weather=ADDRESS');$information = $xml->xpath("/xml_api_reply/weather/current_conditions/condition");echo $information[0]->attributes();点击这里查看详细情况：http://ortanotes.tumblr.com/post/200469319/current-weather-in-3-lines-of-php
随着 Google Maps API 的普及，开发人员常常需要获得某一特定地点的经度和纬度。这个非常有用的函数以某一地址作为参数，返回一个数组，包含经度和纬度数据。
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点击这里查看详细情况：http://snipplr.com/view.php?codeview&id=47806
有些网站或 Web 应用程序需要使用来自其他网站的 favicon 图标。利用 Google 和 PHP 很容易就能搞定，不过前提是 Google 不会连接被重置哦！
function get_favicon($url){$url = str_replace("http://",'',$url);return "http://www.google.com/s2/favicons?domain=".$url;}点击这里查看详细情况：http://snipplr.com/view.php?codeview&id=45928
参考资料：10 super useful PHP snippets