php 函数使用方法与函数定义方法

function "function_name" (arg1, arg2...)
{
[code to execute]
return [final_result];
}

function double_this_number($input_number)
{
return $input_number*2;
}

$x = 10;
$y = double_this_number($x);
print $y;

function safePost($v=0)
{
if( $v==0 )
{
$protected = array("_GET", "_POST", "_SERVER", "_COOKIE", "_FILES", "_ENV", "GLOBALS");
foreach($protected as $var) {
if(isset($_REQUEST[$var]) || isset($_FILES[$var]))
{
die("Access denied");
}
}
}
}