PHP学习笔记之php变量用法_PHP教程

$var='Jim';
$VAR='Kimi;
echo "$var,$VAR";//输出“Jim,Kimi"
?>

$a = "China"; //变量a
$b = "a"; //变量b
$China = "I'm Chinese !"; //变量China
$f = "b"; //变量f

echo $a."
"; //输出 China
echo $$a."
"; //输出 I'm Chinese --这里像要当做可变变量解析，必须在前面多加一个$符号
$a = "f"; //改变变量指向的名称(这里就是可变变量的应用)
echo $$a."
"; //经过上面指向变量f后输出 b
$a = "b"; //同上
echo $$a."

"; //输出 a

echo $b."
"; //输出 a
echo $$b."
"; //输出 b
echo $$$b."

"; //输出 a

echo $f."
"; //输出 b
echo $$f."
"; //输出 a
echo $$$f."
"; //输出 b
echo $$$$f."

"; //输出 a

$$a = "China"; //前面最后一个已经更改了变量为b所谓$$a=$b 也就是改变的$b的值
echo $b."
"; //输出 China
echo $$b; //输出 I'm Chinese
?>

$name = 'man';
$$name = 'abc'; //如果事先没有man这个变量。就新建一个man变量。 然后把abc赋值过去
$$$name = 'def';
echo $man."
"; //输出abc
echo $abc; //输出def

echo "

function b()
{
echo "这是B";
}
function c($name = "China") //设默认值
{
echo "这是$name";
}

$a = 'b';
$a(); //找值所在的函数
$a = 'c';
$a(); ?>

name:


pwd :


tag :

$a = 1;
include "b.inc";
?>

$a = 1; /* global scope */

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

Test();
?>

$a = 1;
$b = 2;

function Sum()
{
global $a, $b;

$b = $a + $b;
}

Sum();
echo $b;
?>

$a = 1;
$b = 2;

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

Sum();
echo $b;
?>

function test_global()
{
// 大多数的预定义变量并不 "super"，它们需要用 'global' 关键字来使它们在函数的本地区域中有效。
global $HTTP_POST_VARS;

print $HTTP_POST_VARS['name'];

// Superglobals 在任何范围内都有效，它们并不需要 'global' 声明。Superglobals 是在 PHP 4.1.0 引入的。
print $_POST['name'];
}
?>

function Test()
{
static $count = 0;

$count++;
echo $count;
if ($count <10) {
Test ();
}
$count--;
}
?>

function foo(){
static $int = 0; // correct
static $int = 1+2; // wrong (as it is an expression)
static $int = sqrt(121); // wrong (as it is an expression too)

$int++;
echo $int;
}
?>

function test_global_ref() {
global $obj;
$obj = &new stdclass;
}

function test_global_noref() {
global $obj;
$obj = new stdclass;
}

test_global_ref();
var_dump($obj);
test_global_noref();
var_dump($obj);
?>

function &get_instance_ref() {
static $obj;

echo "Static object: ";
var_dump($obj);
if (!isset($obj)) {
// 将一个引用赋值给静态变量
$obj = &new stdclass;
}
$obj->property++;
return $obj;
}

function &get_instance_noref() {
static $obj;

echo "Static object: ";
var_dump($obj);
if (!isset($obj)) {
// 将一个对象赋值给静态变量
$obj = new stdclass;
}
$obj->property++;
return $obj;
}

$obj1 = get_instance_ref();
$still_obj1 = get_instance_ref();
echo "/n";
$obj2 = get_instance_noref();
$still_obj2 = get_instance_noref();
?>