php percentage chance

Question

This is really more a question of approach, but I\'m presenting it in php.

Suppose we had a list of four percentages that a give event will occur on iteration.

Answer 1

$arr = array('walk the dog'=>25,'read the paper'=>25,'listen to music'=>50);
$rand = rand(1,100);
$sum = 0;
$action = '';

foreach ($arr as $k => $v) {
    $sum .= $k;
    if ($sum <= $k)
        $action = $v;
}

Removed those with a key value of zero, and multiplied the key-value with 100 to make it more readable.