7个超级实用的PHP代码片段分享(1)_PHP教程

1、超级简单的页面缓存

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。

    // 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();  
?>  
      
        output all your html here.  
      
    // We're done! Save the cached content to a file  
    $fp = fopen($cachefile, 'w');  
    fwrite($fp, ob_get_contents());  
    fclose($fp);  
    // finally send browser output  
    ob_end_flush();  
?> 

点击这里查看详细情况：http://wesbos.com/simple-php-page-caching-technique/

2、在 PHP 中计算距离

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

3、将秒数转换为时间(年、月、日、小时…)

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

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