PHP中数组排序函数详解

<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
arsort($fruits);
var_dump($fruits);
?>
结果
array
'a' => string 'orange' (length=6)
'd' => string 'lemon' (length=5)
'b' => string 'banana' (length=6)
'c' => string 'apple' (length=5)

--------------------ksort按照数组的key升序排列-------------- <?php$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
ksort($fruits);
var_dump($fruits);
?>
结果
array
'a' => string 'orange' (length=6)
'b' => string 'banana' (length=6)
'c' => string 'apple' (length=5)
'd' => string 'lemon' (length=5)

<?php
$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
krsort($fruits);
var_dump($fruits);
?>

array
'd' => string 'lemon' (length=5)
'c' => string 'apple' (length=5)
'b' => string 'banana' (length=6)
'a' => string 'orange' (length=6)

<?php
function cmp($a, $b)
{
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}

$a = array(3, 2, 5, 6, 1);

usort($a, "cmp");

var_dump($a);
?>
结果：
array
0 => int 1
1 => int 2
2 => int 3
3 => int 5
4 => int 6

<?php
function cmp($a, $b)
{
$a = preg_replace('@^(a|an|the) @', '', $a);
$b = preg_replace('@^(a|an|the) @', '', $b);
return strcasecmp($a, $b);
}

$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);

uksort($a, "cmp");

var_dump($a);
?>
结果：
array
'an apple' => int 3
'a banana' => int 4
'the Earth' => int 2
'John' => int 1

<?php
// Comparison function
function cmp($a, $b) {
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}

// Array to be sorted
$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);
var_dump($array);

// Sort and print the resulting array
uasort($array, 'cmp');
var_dump($array);
?>
结果：
array
'a' => int 4
'b' => int 8
'c' => int -1
'd' => int -9
'e' => int 2
'f' => int 5
'g' => int 3
'h' => int -4
array
'd' => int -9
'h' => int -4
'c' => int -1
'e' => int 2
'g' => int 3
'a' => int 4
'f' => int 5
'b' => int 8

<?php
$ar = array(
array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);

array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC);
var_dump($ar);
?>
结果：
array
0 =>
array
0 => string '10' (length=2)
1 => int 100
2 => int 100
3 => int 11
4 => string 'a' (length=1)
1 =>
array
0 => int 1

function page_init()
 {   
     $url = $_SERVER['REQUEST_URI'];//子url，该参数一般是唯一的
     $pageid = md5($url);
     $dir = str_replace('/','_',substr($_SERVER['SCRIPT_NAME'],1,-4));
         //目录命名方式，如exp_index
     if(!file_exists($pd = PAGE_PATH.$dir.'/'))@mkdir($pd,0777) or die("$pd目录创建失败");
         //如cache/page/exp_index/
     define('PAGE_FILE',$pd.$pageid.'.html');
     　　//如cache/page/exp_index/cc8ef22b405566745ed21305dd248f0e.html
     $contents = file_get_contents(PAGE_FILE);//读出
 
     if($contents && substr($contents, 13, 10) > time() )//对应page_cache()函数中加上的自定义头部
     {
         echo substr($contents, 27);
         exit(0);
     }
     return true;   
 }

function page_cache($ttl = 0)
 {   
     $ttl = $ttl ? $ttl : PAGE_TTL;//缓存时间，默认3600s
     $contents = ob_get_contents();//从缓存中获取内容
     $contents = "<!--page_ttl:".(time() + $ttl)."-->n".$contents;
     　　//加上自定义头部：过期时间=生成时间+缓存时间
     file_put_contents(PAGE_FILE, $contents);//写入缓存文件中
     ob_end_flush();//释放缓存
 }

<?php
      page_init();//页面缓存初始化
      ob_start();//开启缓存       
 
      ...//代码段
 
      page_cache(60);//一般是最后一行
 
?>

<?php
$_time =10;
$dir="D:\php\";

function cache_start($_time, $dir)
{
  $cachefile = $dir.'/'.sha1($_SERVER['REQUEST_URI']).'.html';
  $cachetime = $_time;
  ob_start();
  if(file_exists($cachefile) && (time()-filemtime($cachefile) < $cachetime))
  {
    include($cachefile);
    ob_end_flush();
    exit;
  }
}

function cache_end($dir)
{
  $cachefile = $dir.'/'.sha1($_SERVER['REQUEST_URI']).'.html';
  $fp = fopen($cachefile, 'w');
  fwrite($fp, ob_get_contents());
  fclose($fp);
  ob_end_flush();
}

cache_start($_time, $dir);
//以下是输出的内容，放在cache_start和cache_end两个方法之间
for ($i=0;$i<5;$i++)
{
  echo $i;
  sleep(1);
}
cache_end($dir);
?>

<?php
ob_start();
/**
* @author 何名慧
* @copyright 2009-3-13
* @param string $cache_folder 缓文件夹
* @param int $cache_create_time 文件缓存时间
* @example $cache=new Esj_Cache('./_cache',100)
* @example $cache->read_cache() 读取缓存并输出
* @example $cache->creatre_cache() 创建缓存文件(放在文件未尾)
* @example $cache->list_file() 返回所有缓存文件列表
* @example $cache->del_file() 删除所有缓存文件
*/

class Esj_Cache{
private $cache_folder=null;//cacher文件夹
private $wroot_dir=null;//站点目录
private $cacher_create_time=null;//cacher文件的建立时间

public function __construct($cache_foldername,$cacher_time=100)
{
ob_start();
$this->wroot_dir=$_SERVER['DOCUMENT_ROOT'];
$this->cache_folder=$cache_foldername;
$this->cacher_create_time=$cacher_time;
}

public function read_cache()
{
try {
if(self::create_folder($this->cache_folder))
{
self::get_cache();//输出缓存文件信息
}else
{
echo "缓存文件夹创建失败!";
return false;
}

}catch(Exception $e){
echo $e;
return false;
}
}

//测试缓存文件夹是否存在
private function exist_folder($foler)
{
if(file_exists($this->wroot_dir."/".$foler)){
return true;
}else {
return false;
}
}

//建立一个新的文件夹
private function create_folder($foler)
{
if(!self::exist_folder($foler))
{
try{
mkdir($this->wroot_dir."/".$foler,0777);
chmod($this->wroot_dir."/".$foler,0777);
return true;
}catch (Exception $e)
{
self::get_cache();//输出缓存
return false;
}
return false;
}
else
{
return true;
}
}

//读取缓存文件
private function get_cache()
{
$file_name=self::get_filename();
if (file_exists($file_name)&&((filemtime($file_name)+$this->cacher_create_time) > time()))
{
$content=file_get_contents($file_name);
if($content)
{
echo $content;
ob_end_flush();
exit;
}else
{
echo "文件读取失败";
exit;

}

}
}

//返回文件的名字
private function get_filename()
{
$filename=$file_name=$this->wroot_dir.'/'.$this->cache_folder.'/'.md5($_SERVER['QUERY_STRING']).".html";
return $filename;
}

//建立缓存文件
public function create_cache()
{
$filename=self::get_filename();
if($filename!="")
{
try{
file_put_contents($filename,ob_get_contents());
return true;
}catch (Exception $e)
{
echo "写缓存失败:".$e;
exit();
}
return true;
}
}

// 取得缓存中的所有文件
public function list_file()
{
$path=$this->cache_folder;
if ($handle = opendir($path)) {
while (false !== ($file = readdir($handle))) {
if($file!="." && $file!="..") {
$path1=$path."/".$file;
if(file_exists($path1))
{
$result[]=$file;
}
}
}
closedir($handle);
}
return $result;
}

//删除缓存中的所有文件
public function del_file()
{
$path=$this->cache_folder;
if ($handle = opendir($path)) {
while (false !== ($file = readdir($handle))) {
if($file!="." && $file!="..") {
$path1=$path."/".$file;
if(file_exists($path1))
{
unlink($path1);
}
}
}
closedir($handle);
}
return true;
}

}

?>

<?PHP
 
class MemcacheModel {
private $mc = null;
/**
* 构造方法,用于添加服务器并创建memcahced对象
*/
function __construct(){
$params = func_get_args();
$mc = new Memcache;
//如果有多个memcache服务器
if( count($params) > 1){
foreach ($params as $v){
call_user_func_array(array($mc, 'addServer'), $v);
}
//如果只有一个memcache服务器
} else {
call_user_func_array(array($mc, 'addServer'), $params[0]);
}
$this->mc=$mc;
}
/**
* 获取memcached对象
* @return object memcached对象
*/
function getMem(){
return $this->mc;
}
/**
* 检查mem是否连接成功
* @return bool 连接成功返回true,否则返回false
*/
function mem_connect_error(){
$stats=$this->mc->getStats();
if(empty($stats)){
return false;
}else{
return true;
}
}

private function addKey($tabName, $key){
$keys=$this->mc->get($tabName);
if(empty($keys)){
$keys=array();
}
//如果key不存在,就添加一个
if(!in_array($key, $keys)) {
$keys[]=$key;  //将新的key添加到本表的keys中
$this->mc->set($tabName, $keys, MEMCACHE_COMPRESSED, 0);
return true;   //不存在返回true
}else{
return false;  //存在返回false
}
}
/**
* 向memcache中添加数据
* @param string $tabName 需要缓存数据表的表名
* @param string $sql 使用sql作为memcache的key
* @param mixed $data 需要缓存的数据
*/
function addCache($tabName, $sql, $data){
$key=md5($sql);
//如果不存在
if($this->addKey($tabName, $key)){
$this->mc->set($key, $data, MEMCACHE_COMPRESSED, 0);
}
}
/**
* 获取memcahce中保存的数据
* @param string $sql 使用SQL的key
* @return mixed 返回缓存中的数据
*/
function getCache($sql){
$key=md5($sql);
return $this->mc->get($key);
}

/**
* 删除和同一个表相关的所有缓存
* @param string $tabName 数据表的表名
*/
function delCache($tabName){
$keys=$this->mc->get($tabName);
//删除同一个表的所有缓存
if(!empty($keys)){
foreach($keys as $key){
$this->mc->delete($key, 0); //0 表示立刻删除
}
}
//删除表的所有sql的key
$this->mc->delete($tabName, 0);
}
/**
* 删除单独一个语句的缓存
* @param string $sql 执行的SQL语句
*/
function delone($sql){
$key=md5($sql);
$this->mc->delete($key, 0); //0 表示立刻删除
}
}

<?php
$a = 1;
include 'b.inc';
?>

<?php
$a = 1; /* global scope */

function Test()
{
    echo $a; /* reference to local scope variable */
}

Test();
?>

<?php
$a = 1;
$b = 2;

function Sum()
{
    global $a, $b;

    $b = $a + $b;
}

Sum();
echo $b;
?>

<?php
$a = 1;
$b = 2;

function Sum()
{
    $GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
}

Sum();
echo $b;
?>