7个超级实用的PHP代码片段分享

网络整理 - 07-26
   

  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。

<?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 output 
    ob_end_flush(); 
?>

  点击这里查看详细情况:

  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";

  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; 
  } 
}

  4、强制下载文件