Add slashes to date string containing only numbers

Question

I got this variable:

$payments['date'] = 21062013

The problem:

Its a date, so I want to add slashes to this string.

How I'm trying:

echo $paymentdate = substr($payments['date'],2)+/+substr($payments['date'],4)+/substr($payments['date'],8);

It's not working, can some one help?

my full code:

$i = 0;
foreach($SQL->query('SELECT id, form, email, value, data, date, compensated from payments where compensated="N"') as $payments)
{
 $i++;
 $paymentdate = substr($payments['date'], 0, 2)."/".substr($payments['date'], 2, 2)."/".substr($payments['date'], 2, 8);
 echo '<tr bgcolor="' . (is_int($i / 2) ? $config['site']['darkborder'] : $config['site']['lightborder']) . '">  
  <td>' . $payments['id'] . '</td>
  <td>' . $payments['form'] . '</td>
  <td>' . $payments['email'] . '</td>
  <td>' . $payments['value'] . '</td>
  <td>' . $paymentdate .'</td>
  <td>' . $payments['data'] . '</td>
  <td>' . $payments['compensated'] . '</td>
  <td>a</td>
 </tr>';
}

Answer 1

This should work for you;

echo $paymentdate = substr($payments['date'], 0, 2)."/".substr($payments['date'], 2, 2)."/".substr($payments['date'], 4, 4);