擬似乱数

<html><body style="font-size:32px; line-height:32px;">
<?php
// set color
    $colors = array("red", "blue", "yellow", "green", "black");
// draw 16x16
    for ($i = 0; $i < 256; $i++){
        $r = rand(0, count($colors)-1);
        $c = $colors&#91;$r&#93;;
        echo "<span style='color:$c'>■</span>";
        if ($i % 16 == 15) echo "<br>";
    }
?></body></html>