function str_random($a = 8) {
$b = NULL;
$c = $d = NULL;
for ($i = 0; $i < $a; $i++) {
$c = chr(rand(48, 122));
while (!ereg("[a-zA-Z0-9]", $c)) {
if ($c == $d) continue;
$c = chr(rand(48, 90));
}
$b .= $c;
$d = $c;
}
return $b;
}
