Random numbers to 5

[jamesm87]

Hey,

What would be the best way of randomizing numbers without repeating for example..

Box 1 = 3

Box 2 = 4
Box 3 = 2
Box 4 = 5
Box 5 = 1

So 5 box's (Lets say $box[1] etc) must equal a number from 1 to 5 but can not be repeated in any of the other box's so it has to be unique.

Usually I can work this stuff out, but this has done my nut in after an hour trying to figure out a way! I think using "IF rand number is same as last box's then random again" is so unefficient, is there another way?

Thanks!

[Shrike]

How about this

$box = array( 'a', 'b', 'c', 'd', 'e' );
$keys = array_keys( $box );
shuffle( $keys );
for( $i = 0, $x = sizeof( $box ); $i < $x; $i++ )
{
  $newbox[$box[$i]] = $keys[$i];
}
print_r( $newbox );

Todays programming challenge: do this task in the style of Monty Python.

[laserlight]

You can use [man]range/man to generate an array of the numbers you want, and then [man]shuffle/man the array elements.

If you do not necessarily want a specific range of numbers, then you can use [man]mt_rand/man to generate a number, use [man]in_array/man to check that it was not generated previously, and if so append it to the array of numbers.

[Installer]

Monty Python might do it like this:

$num_boxes = 5;
$boxes = array();
for ($i = 1; $i <= $num_boxes; $i++) {
    do {
        $num = mt_rand(1, $num_boxes);
    } while (in_array($num, $boxes));
    $boxes[$i] = $num;
}

foreach ($boxes as $key => $value) {
    echo 'Box ' . $key . ' = ' . $value . '<br />';
}

Warning: Don't do it this way, especially if $num_boxes is large.