PHP学习笔记-001:示例中了解常量以变量

PHP学习笔记-001:示例中了解常量以变量

源自：杨志刚博客 （http://yangzhigang.cublog.cn）

 

echo PHP_VERSION."\n";                       /* PHP内置常量：PHP_VERSION */
echo PHP_OS;                                 /* PHP内置常量：PHP_OS */
echo "\n";

 

 

define("copyright","yangzhigang.cublog.cn");  /* 自定义常量：copyright */
define('pai',3.1415);                         /* 自定义常量：pai */

echo copyright;
echo "\n";
echo COPYRIGHT;                               /* 常量名区分大小写,copyright与COPYRIGHT不一样 */
echo "\n";
echo pai;
echo "\n";

 

 

class foo{                                   /* 定义一个class:foo */
 function do_foo(){
  echo "doing foo";
 }
}
$bar=new foo();
$bar ->do_foo();

echo "\n";

 

function myfunc(){                          /* 定义一个function:myfunc */ 

 global $PHP_OS;                            /* 声明函数中引用全局的变最  */
 echo PHP_OS;
}
myfunc();
echo "\n";

 

function func1(){
 static $ha;                          /* 将变量静态化 */

 $ha.="ha,";
 echo $ha;
}
func1();
func1();
echo "\n";

$a = "hello";
$$a = "world";                          /* 变量的变量 */
echo "$a,$hello";
echo "\n";
echo "$a,${$a}";
?>