6 三章 变量作用域

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变量作用域：
1. 局部变量
2. 函数参数
4. 全局变量
5. 静态变量
6. PHP的超级全局变量


 test.rar  

局部变量

$x = 4;
    function assignx()
    {
        $x = 0;
        printf("\$x inside funcitong is %d ",$x);//<br />换行
    }
    assignx();
    printf("\$x outside of funciton is %d ",$x);

$x inside funcitong is 0
$x outside of funciton is 4

函数参数

function x10($value)
    {
        $value = $value * 10;
        return $value;
    }
    $test_value = x10(10);
    printf("test_value=%d ",$test_value);

test_value=100

全局变量

$somevar = 15;
    function addit()
    {
        GLOBAL $somevar;
        $somevar++;
        echo "somevar is $somevar ";
    }
    addit();

somevar is 16

静态变量

function keep_track()
    {
        STATIC $count = 0;
        $count++;
        echo $count;
        echo "";
    }
    keep_track();
    keep_track();

1
2

PHP的超级全局变量

printf("your IP address is :%s ",$_SERVER['REMOTE_ADDR']);
    printf("your browser is :%s ",$_SERVER['HTTP_USER_AGENT']);
    foreach($_SERVER as $var=>$value)
    {
        echo "$var => $value ";
    }

your IP address is :127.0.0.1
your browser is :Mozilla/5.0 (X11; U; Linux i686; zh-CN; rv:1.9.2.18) Gecko/20110628 Ubuntu/10.10 (maverick) Firefox/3.6.18
HTTP_HOST => localhost
HTTP_USER_AGENT => Mozilla/5.0 (X11; U; Linux i686; zh-CN; rv:1.9.2.18) Gecko/20110628 Ubuntu/10.10 (maverick) Firefox/3.6.18
HTTP_ACCEPT => text/html,a