从数组中随机选择

Question

There is this function :

mt_rand(1,5)

=> randomly selects between 1 and 5.

and another method:

$items = array(1, 4, 5, 7, 8);
echo $items[array_rand($items)];

My question is about second method. I want to use it in this way. echo array_rand(1,4,5,7,8);

Is there a way to do this, or how can I do it? I would like to use the function without defining the array first. Everything in one place. thanks!

Note: I want to use it for unordered list.

Answer 1

You can flip the array, then use array_rand(), this will inverse the key-value pairs (so the key becomes the value, and vice-versa). This will mean that when you use array_rand(), you get the new key - which was originally the value.

echo array_rand(array_flip($items));

• Live demo at https://3v4l.org/7RSVY

If you want to define a function with a variable number of parameters, you can do that too, by using func_get_args().

function random_value() {
    // If there were no values returned, return false.
    if (func_num_args() == 0) {
        return false;
    }

    // Get all the values supplied
    $values = func_get_args();
    $random = array_rand($values);
    return $values[$random];
}

• Live demo at https://3v4l.org/b63WX

Though you can just define the array inline, by doing

echo array_rand(array_flip([1, 3, 7, 8]));