php中构造函数与析构函数详解

<?php
 class des{
  function __destruct(){
   echo "运行结束，执行析构函数";
  }
 }
 $p=new des(); /* 实例化类 */
 $sum=0;
 for($i=0;$i<10;$i++){
  $sum=$sum+$i;
  echo $sum ."<br>";
 }
?>

<?php
 class des{
  function __destruct(){
   echo "对象被销毁，执行析构函数<br>";
  }
 }
 $p=new des(); /* 实例化类 */
 echo "程序开始<br>";
 unset($p); /* 销毁变量$p */
 echo "程序结束";
?>

function __construct([argument1,argument2,argument3]){
    /* class initialization code */
}

<?php
 class user{
  public $name;
  private $password;
  private $login;
  public function __construct($name,$password){
   $this->name=$name;
   $this->password=$password;
   $this->login=time();
  }
  function getlogin(){
   return(date('M d,Y',$this->login));
  }
 }
 $user=new user('Marry','888888');
 echo "用户名： ". $user->name. "<br>";
 print("访问时间". $user->getlogin());
?>

<?php
 class task1{
  public function __construct(){
   echo "today is Monday". "<br>";
  }
 }
 class task2 extends task1{
  function __construct(){
   parent::__construct(); /* 调用父类构造函数 */
   echo "I must work!";
  }
 }
 new task2;
?>

<?php
 class Date{
  const M="Monday";
 }
 echo "today is ".Date::M;
?>

<?php            
 class me{          
 protected $Money =100;       
 protected $price1=60;        
 
 public function Sell($price){      
  if($this->price1<=$price){      
   echo "好，卖给你了。<br>";     
   $this->Money = $this->Money+$price;  
   return "我现在总共有 ".$this->Money." 元钱"; 
  }
 else{           
  echo "我不卖 ,$price 太便宜了<br>";    
  return "现在我还是 ".$this->Money." 元钱";  
   }
  }
 }
 
 $now=new me;          
 echo $now->Sell(30);         
?>

<?php
 class ex1{
  final function fn1(){
   return "php";
  }
 }
 class ex2 extends ex1{
  function fn1(){
   return "html";
  }
 }
 $p= new ex2();
 echo $p->fn1();
?>

<?php
 final class ex1{
  private $name;
 }
 class ex2 extends ex1{
  private $age;
 }
?>

<?           
 class user{        
 private static $count = 10;    
 private static $sum=1;     
 public function __construct(){    
 for($i=1;$i<11;$i++){      
  self::$sum = self::$sum * self::$count; /* 调用静态变量 */
  self::$count--;      
 }   
 }
 public function getCount(){    
  return self::$sum;     
 }
 }
 $user1 = new user();      
 echo $user1->getCount();  
?>

<?             
 class Math{           
  public static function sum($num1,$num2){  
  return $num1 + $num2;       
  }
  public static function product($num1,$num2){
  return $num1 * $num2;       
 }
  }   
 $a = 88;           
 $b = 100;          
 echo "两数之和为： ";        
 echo "<br>";          
 echo Math::sum($a,$b);       
 echo "<P>";          
 $a = 66;           
 $b = 88;           
 echo "两数之积为： ";        
 echo "<br>";          
 echo Math::product($a,$b);       
?>

<?php
 class user{
  private $n;
  function __construct(){
   $name="Mike";
   echo $this->n=$name;
  }
 }
 $p=new user();
?>

<?php
 class cal{
  public function sum($a,$b){
   return $a+$b;
  }
  public function prt($a,$c){
   return $a*$c;
  }
  public function result($a,$b,$c){
   $a=$this->sum($a,$b);
   return $this->prt($a,$c);
  }
 }
 $c=new cal();
 echo "(2+3)*10= " .$c->result('2','3','10');
?>

function 函数名(参数){
 语句体
}

<?php
 function e(){
  $i=5+6;
  echo $i;
 }
 e();
?>

<?php
 function sum($num,$price){
  $total=$num*$price;
  echo "总价格为：$total";
 }
 sum(10,78);
?>

<?php
 function add($a,$b=10){  /* 定义变量$b默认参数 */
  $sum=$a+$b;
  echo $sum ."<br>";
 }
 add(1,5);   /* 按值传递参数代替默认参数 */
 add(1);    /* 没有给$b传递参数将采用默认值 */
?>

<?php
 function add($a,$b=10){  
  $sum=$a+$b;
  return $sum; /* 将$sum的值赋给函数 */
 }
 $sum=add(1,5);  /* 这里变量$sum得到函数的值 */   
 echo $sum ."<br>";
?>

<?php
 function volume($l,$w){
  function height($a){
   $a=$a/2;
   return $a;
  }
  $a=$l*$w;
  $v=$a*height($a);
  echo $v;
 }
 volume(8,3);
?>

<?php
 function calculate($n){
  if($n==0)
  return 1;
  else
  return $n*calculate($n-1);
 }
 $s=calculate(3);
 echo $s;
?>

<?php
 setcookie("c1","my name is Rose",time()+3600);
 /* 建立一个名称为"c1"的cookie 过期时间为3600秒 */
?>

<?php
 echo "c1的Cookie值是 " .$_COOKIE['c1'] ."<br>";
 echo "c2的Cookie值是 " .$_COOKIE['c2'];
?>

<?php
 $count=$_COOKIE['user'];
 $count++;
 setcookie("user",$count,time()+3600); 
 echo "这是你的第 $count 次访问!";
?>