PHP strtotime仅在添加天数时正确转换

Question

I am using strtotime in PHP, and getting two different result from the same input. I cannot work out why.

$startDate = 1468467219;
$oldDate = date('d/m/Y', strtotime($startDate));
$newDate = date('d/m/Y', strtotime('+3 weekdays', $startDate));

The original date is 14/07/2016 01.33 PM

$newDate is returning 19/07/2016 As expected.

$oldDate is returning 01/01/1970 Not the expected result - should be 14/07/2016.

I have tried other functions inside strtotime and they all produce the correct result. What am I missing? Why can I not simply just pass 1468467219 to strtotime without modifying it?

Answer 1

You are misusing strtotime. This function takes a string representation of a date, and returns a timestamp. Instead you're feeding it a timestamp

$startDate = 1468467219;
$oldDate = date('d/m/Y', strtotime($startDate));

Since no common date format is expressed as "today is 1468467219", the function is unable to parse it and returns false.

var_dump(strtotime($startDate)) //<-- boolean FALSE

When you go on to feed FALSE to the date function, it can't parse it either, so it returns the wrong date: 01/01/1970.

To get the result you need just feed the timestamp directly to date:

$oldDate = date('d/m/Y', $startDate);