php中var_dump()函数的详解说明

<?php
$a = "alsdflasdf;a";
$b = var_dump($a);
echo "<br>";
//var_dump($c);
$d=var_dump($c);
echo "<br>";
echo $a;
echo "<br>";
echo $b;
echo "<br>";
输出：
string(12) "alsdflasdf;a"
NULL
alsdflasdf;a

<pre>
<?php
$a = array (1, 2, array ("a", "b", "c"));
var_dump ($a);

/* 输出：
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  array(3) {
    [0]=>
    string(1) "a"
    [1]=>
    string(1) "b"
    [2]=>
    string(1) "c"
  }
}

*/

$b = 3.1;
$c = TRUE;
var_dump($b,$c);

/* 输出：
float(3.1)
bool(true)

*/
?>
</pre> 

<?
set_time_limit(50);
$a = array(1,2,3);
$b = array('a'=>1, 'b'=>2, 'c'=>3);
$c = array('a'=>array(1,2,3), 'b'=>array(4,5,6));

$time1 = microtime(true);

$times = 1000000; #10w

for($i=1; $i<=$times; $i++){
 $A = var_export($a, true);
}

$time2 = microtime(true);

for($i=1; $i<=$times; $i++){
 $B = var_export($b, true);
}

$time3 = microtime(true);

for($i=1; $i<=$times; $i++){
 $C = var_export($c, true);
}

$time4 = microtime(true);

for($i=1; $i<=$times; $i++){
 $X = serialize($a);
}

$time5 = microtime(true);

for($i=1; $i<=$times; $i++){
 $Y = serialize($b);
}

$time6 = microtime(true);

for($i=1; $i<=$times; $i++){
 $Z = serialize($c);
}

$time7 = microtime(true);

for($i=1; $i<=$times; $i++){
 $O = unserialize($X);
}

$time8 = microtime(true);

for($i=1; $i<=$times; $i++){
 $P = unserialize($Y);
}

$time9 = microtime(true);

for($i=1; $i<=$times; $i++){
 $Q = unserialize($Z);
}
$time10 = microtime(true);

$var_export_time['a'] = $time2 - $time1;
$var_export_time['b'] = $time3 - $time2;
$var_export_time['c'] = $time4 - $time3;

$serialize_time['a'] = $time5 - $time4;
$serialize_time['b'] = $time6 - $time5;
$serialize_time['c'] = $time7 - $time6;

$unserialize_time['a'] = $time8 - $time7;
$unserialize_time['b'] = $time9 - $time8;
$unserialize_time['c'] = $time10 - $time9;
print_r($var_export_time);
print_r($serialize_time);
print_r($unserialize_time);
?>
output:
Array(    [a] => 3.3401498794556    [b] => 5.1394801139832    [c] => 8.8483898639679)Array(    [a] => 1.6063709259033    [b] => 1.7033960819244    [c] => 3.4534389972687)Array(    [a] => 1.6037359237671    [b] => 1.817803144455    [c] => 3.7992968559265)

< ?php
$file_contents = file_get_contents(''http://www.111cn.net/'');
echo $file_contents;
?>

function file_get_content($url) {
if (function_exists(‘file_get_contents')) {
$file_contents = @file_get_contents($url);
}
if ($file_contents == ”) {
$ch = curl_init();
$timeout = 30;
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
$file_contents = curl_exec($ch);
curl_close($ch);
}
return $file_contents;
}

<?php
echo dirname("c:/testweb/home.php");
echo dirname("/testweb/home.php");
?>

输出：

c:/testweb
/testweb

<?php
$basedir = dirname(__FILE__);
echo $basedir
//将在页面打印出一个这个文件所在绝对路径!
?>

<?php
class autoload
{
  public static function load( $class name )
  {
    $filename = $classname.".class.php";
    if (file_exists($filename )) {
      require_once $filename ;
    }
  }
}
 
function __autoload( $class name )
{
    // 这个是默认的 autoload 方法
    $filename = $classname.".class.php";
    if (file_exists($filename )) {
      require_once $filename ;
    }
}
 
// 注册一个 autoloader
spl_autoload_register( 'autoload::load' );
spl_autoload_register( '__autoload' );
 // 注：下面的类看上去没有定义，但其实系统根据sql_autoload_register提供的路径会自动去搜索
//foo.class.php文件，如果没找到才报错。
$foo = new foo();
$foo ->bar();
?>

function my_own_loader($classname)
{
    $class_file = strtolower($classname).".php";
    if (file_exists($class_file)){
        require_once($class_file);
    }
}
 
spl_autoload_register("my_own_loader");
 
$a = new A();

class Loader
{
    public static function my_own_loader($classname)
    {
        $class_file = strtolower($classname).".php";
        if (file_exists($class_file)){
            require_once($class_file);
        }
    }
}
 
// 通过数组的形式传递类和方法的名称
spl_autoload_register(array("Loader","my_own_loader"));
$a = new A();

static public function myAutoload($class){
  if(file_exists(APPPATH.'models'.DIRECATORY_SEPARATOR.$class.'.php')){
     require_once APPPATH.'models'.DIRECATORY_SEPARATOR.$class.'.php';
  }
}
/**
* 注册加载器
*/
static public function autoload(){
   spl_autoload_register(array(__CLASS__, 'myAutoload'));
   if(class_exists('__autoload')){
      spl_autoload_register('__autoload');
   }
}
MY_Controller::autoload();

view plaincopy to clipboardprint?
<?php  
function loader($class)  
{  
$file = $class . '.php';  
if (is_file($file)) {  
require_once($file);  
}  
}  

spl_autoload_register('loader');  

$a = new A();

<?php
function loader($class)
{
$file = $class . '.php';
if (is_file($file)) {
require_once($file);
}
}

spl_autoload_register('loader');

$a = new A();

view plaincopy to clipboardprint?
<?php  
class Loader  
{  
public static function loadClass($class)  
{  
$file = $class . '.php';  
if (is_file($file)) {  
require_once($file);  
}  
}  
}  

spl_autoload_register(array('Loader', 'loadClass'));  

$a = new A();

<?php
$arr = array("blue","red","green","yellow");
print_r(str_replace("red","pink",$arr,$i));
echo "Replacements: $i";
?>输出：

Array
(
[0] => blue
[1] => pink
[2] => green
[3] => yellow
)
Replacements: 1

<?php
echo substr_replace("Hello world","earth",6);
?>

输出：

Hello earth

<?php
// split the phrase by any number of commas or space characters,
// which include " ", r, t, n and f
$keywords = preg_split ("/[s,]+/", "hypertext language, programming");
?>

<?php
$str = 'string';
$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);
print_r($chars);
?>

<?php
$str = 'hypertext language programming';
$chars = preg_split('/ /', $str, -1, PREG_SPLIT_OFFSET_CAPTURE);
print_r($chars);
?>