How to identify a unix timestamp from a date?

Question

Any ideas how I can make a simple IF-statement that sort 31-10-2017 or 12-01-2016 from 1511431687?

I am converting from a set date, to use unix timestamp, and need a solution to sort out what is what. I want to display the date in human readable format (days/ month/year).

So I have a $data that is inside a loop. It pulls the date from a flat file. The old stuff has just saved the date as a date. For instance 31-10-2017 (exactly like that).

Now I use unix timestamp. For instance 1511431687.

I see people have used a simple IF-statement, but I can not use it as both are 10 units long. Else that would have worked well.

$data = // either a timestamp, or a date in this format: 31-10-2017

if (strlen($data) === 10) // it's a timestamp   
$data =  date("d-m-Y H:i:s", $data);

`if (strpos($data, '-') === false) // it's a timestamp` (assumes positive timestamps); adjust if you might have timestamps before the 1970 timestamp base date — Mark Baker, Dec 07 '17 at 13:26
So you're looking for a regex for date? Or timestamp? Timestamp is shorter, `\d{10}`. — pavel, Dec 07 '17 at 13:27
@RolandStarke: OP wrote _both are 10 units long_, so both are the same length. At least in this case. — pavel, Dec 07 '17 at 13:29
@MarkBaker https://meta.stackexchange.com/questions/230676/hey-you-yeah-you-post-your-answers-as-answers-not-comments/296481#296481 You are not seeking clarification, you are providing a solution. Please post in the correct location. — mickmackusa, Dec 07 '17 at 13:50
Possible duplicate of [$var is valid unix timestamp](https://stackoverflow.com/questions/4123541/var-is-valid-unix-timestamp) — mickmackusa, Dec 07 '17 at 14:09

score 3 · Accepted Answer · answered Dec 07 '17 at 13:33

3

Maybe naive, but a solution might be to check if $data has a numeric value.

if (is_numeric($data)) { // it's a timestamp   
    $data =  date("d-m-Y H:i:s", (int) $data);
}

answered Dec 07 '17 at 13:33

l-x

1,521
9
17

Note that "+0123.45e6" *is numeric* too… – deceze Dec 07 '17 at 13:40
is a hyphen ( - ) a numeric value? – Preben Dec 07 '17 at 13:43
@deceze OP stated he only has to distinguish between a date string and a unix timestamp – l-x Dec 07 '17 at 13:44
@Preben no, it's not. php -r "var_dump(is_numeric('-'));" – l-x Dec 07 '17 at 13:45
@Preben Only at the very start of an otherwise numeric the string (e.g. `-42`). – deceze Dec 07 '17 at 13:45
@l-x, yes. I need only distinguish between two formats: unix timestamp or a date format like 01-12-2017 or 02-11-2018 – Preben Dec 07 '17 at 13:46
@l-x Sure, just pointing it out. `ctype_digit` would be more appropriate IMO. – deceze Dec 07 '17 at 13:46
@deceze `ctype_digit` needs *every* character in the input to be numeric. `ctype_digit('-42') === false`, so valid negative unix timestamps would not be recoginzed – l-x Dec 07 '17 at 13:48
Fair enough. If negative timestamps are supposed to be supported, then I concur. – deceze Dec 07 '17 at 13:49

score 0 · Answer 2 · answered Dec 07 '17 at 13:39

You have several options:

ctype_digit to check whether the string is all digits (probably a UNIX timestamp)
preg_match('/^\d{1,2}-\d{1,2}-\d{4}$/', $date) (either a d-m-Y or m-d-Y date)
checkdate to confirm whether a date you think you've identified is valid

Depending on how many different formats you expect, I'd try in this logical order:

if ctype_digit, check if value is in expected range
- if outside expected range, try dividing by 1000 (timestamps in milliseconds)
otherwise, try matching with a regex in whatever formats you expect
- confirm with checkdate that the values are sensible
finally convert to DateTime object as standardised internal representation

How to identify a unix timestamp from a date?

2 Answers2