17. 缩放图片 
function resize_image($filename, $tmpname, $xmax, $ymax) 
{ 
 $ext = explode(".", $filename); 
 $ext = $ext[count($ext)-1];
if($ext == "jpg" || $ext == "jpeg") 
 $im = imagecreatefromjpeg($tmpname); 
 elseif($ext == "png") 
 $im = imagecreatefrompng($tmpname); 
 elseif($ext == "gif") 
 $im = imagecreatefromgif($tmpname);
$x = imagesx($im); 
 $y = imagesy($im);
if($x <= $xmax && $y <= $ymax) 
 return $im;
if($x >= $y) { 
 $newx = $xmax; 
 $newy = $newx * $y / $x; 
 } 
 else { 
 $newy = $ymax; 
 $newx = $x / $y * $newy; 
 }
$im2 = imagecreatetruecolor($newx, $newy); 
 imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y); 
 return $im2; 
}
18. 使用 mail() 发送邮件 
 之前我们提供了如何使用 Mandrill 发送邮件的 PHP 代码片段,但是如果你不想使用第三方服务,那么可以使用下面的 PHP 代码片段。 
function send_mail($to,$subject,$body)
{
$headers = "From: KOONK\r\n";
$headers .= "Reply-To: blog@koonk.com\r\n";
$headers .= "Return-Path: blog@koonk.com\r\n";
$headers .= "X-Mailer: PHP5\n";
$headers .= 'MIME-Version: 1.0' . "\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
mail($to,$subject,$body,$headers);
}
语法:
<?php
$to = "admin@koonk.com";
$subject = "This is a test mail";
$body = "Hello World!";
send_mail($to,$subject,$body);
?>
19. 把秒转换成天数,小时数和分钟 
function secsToStr($secs) {
 if($secs>=86400){$days=floor($secs/86400);$secs=$secs%86400;$r=$days.' day';if($days<>1){$r.='s';}if($secs>0){$r.=', ';}}
 if($secs>=3600){$hours=floor($secs/3600);$secs=$secs%3600;$r.=$hours.' hour';if($hours<>1){$r.='s';}if($secs>0){$r.=', ';}}
 if($secs>=60){$minutes=floor($secs/60);$secs=$secs%60;$r.=$minutes.' minute';if($minutes<>1){$r.='s';}if($secs>0){$r.=', ';}}
 $r.=$secs.' second';if($secs<>1){$r.='s';}
 return $r;
}
语法: 
<?php
$seconds = "56789";
$output = secsToStr($seconds);
echo $output;
?>
20. 数据库连接 
连接 MySQL 数据库 
<?php
$DBNAME = 'koonk';
$HOST = 'localhost';
$DBUSER = 'root';
$DBPASS = 'koonk';
$CONNECT = mysql_connect($HOST,$DBUSER,$DBPASS);
if(!$CONNECT)
{
 echo 'MySQL Error: '.mysql_error();
}
$SELECT = mysql_select_db($DBNAME);
if(!$SELECT)
{
 echo 'MySQL Error: '.mysql_error();
}
?>
21. 目录清单 
使用下面的 PHP 代码片段可以在一个目录中列出所有文件和文件夹 
function list_files($dir)
{
 if(is_dir($dir))
 {
 if($handle = opendir($dir))
 {
  while(($file = readdir($handle)) !== false)
  {
  if($file != "." && $file != ".." && $file != "Thumbs.db"/*pesky windows, images..*/)
  {
echo '<a target="_blank" href="'https://www.jb51.net/article/.$dir.$file.'">'.$file.'</a>'."\n";
  }
  }
  closedir($handle);
 }
 }
}
语法: 
<?php
 list_files("images/"); //This will list all files of images folder
?>
22. 检测用户语言 
使用下面的 PHP 代码片段可以检测用户浏览器所使用的语言 
function get_client_language($availableLanguages, $default='en'){
 if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
 $langs=explode(',',$_SERVER['HTTP_ACCEPT_LANGUAGE']);
 foreach ($langs as $value){
  $choice=substr($value,0,2);
  if(in_array($choice, $availableLanguages)){
  return $choice;
  }
 }
 } 
 return $default;
}
23. 查看 CSV 文件 
function readCSV($csvFile){
 $file_handle = fopen($csvFile, 'r');
 while (!feof($file_handle) ) {
 $line_of_text[] = fgetcsv($file_handle, 1024);
 }
 fclose($file_handle);
 return $line_of_text;
}
语法:
<?php
$csvFile = "test.csv";
$csv = readCSV($csvFile);
$a = csv[0][0]; // This will get value of Column 1 & Row 1
?>
24. 从 PHP 数据创建 CSV 文件 
function generateCsv($data, $delimiter = ',', $enclosure = '"') {
 $handle = fopen('php://temp', 'r+');
 foreach ($data as $line) {
  fputcsv($handle, $line, $delimiter, $enclosure);
 }
 rewind($handle);
 while (!feof($handle)) {
  $contents .= fread($handle, 8192);
 }
 fclose($handle);
 return $contents;
}
语法:
<?php
$data[0] = "apple";
$data[1] = "oranges";
generateCsv($data, $delimiter = ',', $enclosure = '"');
?>