Question

i have a function

function createRandomString($length) {
    $string = md5(time());
    $highest_startpoint = 32-$length;
    # use hexdec to get a "number only" format
    $randomString = hexdec(substr($string,rand(0,$highest_startpoint),$length));
    return $randomString;
}
$randomID = createRandomString(7);

and i want to be able to use the random string created in other functions

for example:

function new() {
echo '<input name="id" type="text" value="'.$randomID.'" disabled="disabled">';
}

However the random ID does not show up in the new function (aka its blank).

I need to define the random ID as a variable once so that the number remains constant throughout the script since if I defined it in every function you would get a different number using this method.

Is there a way of defining the variable randomID using the script at the top and keeping it constant throughout all functions calling it?

Answer 1

Well, though I’d advise against it, the easiest fix for what you’re trying to do in the new function is:

function new()
{
    global $randomID;
    echo '<input....'.$randomID.'/>';
}

But there are a few more, and better ways to achieve the same result:

using classes:

class randomOutput
{
    protected static $_randomID;
    public function __construct()
    {
        self::$_randomID;//can be initialized here, using the same code you have in your createRandomId function
    }

   public function output()
   {
       echo '<input...'.self::$_randomID.'/>';
   }
}

using arguments, as Zulkhaery Basrul’s answer shows. You can make the argument optional by giving a default value of null in your function defenition.
However, since that answer is now deleted:

function new($id)
{
    echo '<input...'.$id.'/>';
}

//with default val:
function new($id = null)
{
    $id = ($id === null ? createRandomId(7) : $id);
    echo '<input...'.$id.'/>';
}

$randId = createRandomId(7);
new($randId);
//some time later
new($randId);

Declaring constants:

function createRandomString($length)
{
    if (defined(RANDOM_STRING_CONST))
    {
        return RANDOM_STRING_CONST;
    }
    //make your randomID, then:
    define('RANDOM_STRING_CONST',$randomID);
    return RANDOM_STRING_CONST;
}

Classes have constants, too. You can define them in an abstract class, so all child classes have access to the same randomId. As an added bonus (and potential pitfall) class constants, defined at the parent level can be overruled by the child class. So be careful!