PHP5.6新增加可变函数参数

function sum(...$numbers)
{
    $acc = 0;
    foreach( $numbers as $number )
    {
        $acc += $number;
    }
    return $acc;
}

echo sum(1,2,3,4);

function sumNumber($a,$b )
{
    echo $a + $b;
    echo "\n";
}
sumNumber(...[1,2]);

$a = [1,2];
sumNumber(...$a);