Return value of php function_PHP tutorial

function results($string)
{
$result = array();
$result[] = $string;//原字符串
$result[] = strtoupper($string);//全部换成大写
$result[] = strtolower($string);//全部换成小写
$result[] = ucwords($string);//单词的首字母换成大写

return $result;
}
$multi_result = results('The quick brown fox jump over the lazy dog');
print_r($multi_result);
?>

输出结果：
Array
(
[0] => The quick brown fox jump over the lazy dog
[1] => THE QUICK BROWN FOX JUMP OVER THE LAZY DOG
[2] => the quick brown fox jump over the lazy dog
[3] => The Quick Brown Fox Jump Over The Lazy Dog
)

test(&$a,&$b){
   $a = 1000;
   $b = 12000;
   return $a+$b;
}

$a = 10;
$b = 12;

$c = test($a,$b);   //注意这里没有 & 了。

//显示修改后的值
echo $a;
echo $b;      
echo $c;  //这是函数返回值；