Máscara em PHP

function mask($val, $mask)
{
$maskared = ”;
$k = 0;
for($i = 0; $i<=strlen($mask)-1; $i++)
{
if($mask[$i] == ‘#’)
{
if(isset($val[$k]))
$maskared .= $val[$k++];
}
else
{
if(isset($mask[$i]))
$maskared .= $mask[$i];
}
}
return $maskared;
}

$cnpj = “11222333000199”;
$cpf = “00100200300”;
$cep = “08665110”;
$data = “10102010”;

echo mask($cnpj,’##.###.###/####-##’).'<br>’;
echo mask($cpf,’###.###.###-##’).'<br>’;
echo mask($cep,’#####-###’).'<br>’;
echo mask($data,’##/##/####’).'<br>’;

Saídas:
11.222.333/0001-99
001.002.003-00
08665-110
10/10/2010

<?
$data = "10102010";
echo mask($data,'##/##/####');
echo mask($data,'[##][##][####]');
echo mask($data,'(##)(##)(####)');
?>

Conteúdo pertencente à: http://clares.wordpress.com/2010/11/12/php-mascara-cnpj-cpf-data-e-qualquer-outra-coisa/