Função para Validar o CPF

function testaCpf($cpf)
{
$cpf = str_pad(ereg_replace('[^0-9]', '', $cpf), 11, '0', STR_PAD_LEFT);

if (strlen($cpf) != 11 || $cpf == '00000000000' || $cpf == '99999999999') {
return false;
} else {
for ($i = 9; $i 11; $i++) {
for ($tot = 0, $j = 0; $j < $i; $j++) {
$tot += $cpf{$j} * (($i + 1) - $c);
}

$tot = ((10 * $tot) % 11) % 10;

if ($cpf{$j} != $tot) {
return false;
}
}

return true;
}
}