7个超级实用的PHP代码片段分享(1)

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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