php - Adding years to a date resets to 1970-01-01

Question

$somedate = "1980-02-15";
$otherdate = strtotime('+1 year', strtotime($somedate));
echo date('Y-m-d', $otherdate);

outputs

1981-02-15

and

$somedate = "1980-02-15";
$otherdate = strtotime('+2 year', strtotime($somedate));
echo date('Y-m-d', $otherdate); 

outputs

1982-02-15

but

$somedate = "1980-02-15";
$otherdate = strtotime('+75 year', strtotime($somedate));
echo date('Y-m-d', $otherdate); 

outputs

1970-01-01

How to fix?

Answer 1

It's the 2038 bug which is like y2k where systems can't handle dates after that year due to 32 bit limitations. Use the DateTime class instead which does work around this issue.

For PHP 5.3+

$date = new DateTime('1980-02-15');
$date->add(new DateInterval('P75Y'));
echo $date->format('Y-m-d');

For PHP 5.2

$date = new DateTime('1980-02-15');
$date->modify('+75 year');
echo $date->format('Y-m-d');