Damn timestamps and dates! Wheres the extra 70 years coming from!?

[HughbertD]

I have done a calculation of the differnce in time between two timestamps like so,

 

$start = strtotime($row["dateTime"]);
$end = strtotime($row["dateTimeFin"]);

$result = ($end - $start);

$conv=gmdate("m \m\o\\n\\t\h\s d \d\a\y\s H \h\o\u\\r\s\ i \m\i\\n\s\ s \s\e\c\s",$result);		

echo ($conv);

 

I have noticed however that there is always 1 extra day, 1 extra month and 70 years in the result.

 

I only want the days, hours, minutes of the difference, but I tried taking off 3600*24 for the extra day this works for results of more than one day, but if the time difference is less than a day, it displays 31 days.

 

I don't want to use a function to do this.

 

If anyone can help I would appreciate it massively

[thebadbad]

Hi, I believe I already solved this in a previous thread started by you.

 

I subtract 1970 from the years and 1 from the months and days, to compensate for the Unix Epoch (1970-01-01 00:00:00 GMT). Seems like that's the source of your problem too!

[HughbertD]

Hi,

 

Sorry, I realise you made a function to do this.

 

Do I take off,  1970*(365*(3600*24)) ?

 

And then the extra day and month etc?

[thebadbad]

I'm not sure if that will be accurate, since an average year isn't 365 days (it's 365.2425 in the Gregorian calendar). But try it, and make some simple tests to see if it's accurate.

[HughbertD]

I gave it a go, it was 6 years out (!)

 

I sent you a PM btw, just so you know. I simply don't understand why counting the number of seconds from 1970 would make the dates do this.

 

Is it the conversion back from the timestamp which is the problem?

 

 

 

 

 

[thebadbad]

I will try to elaborate on the epoch mystery here, for everyone to see.

 

A Unix timestamp (strtotime() creates this) is the number of seconds elapsed from the Unix epoch to a given time. An epoch is a reference date/time, and the Unix epoch were at 1970-01-01 00:00:00 UTC (this is a tricky definition, since UTC did not exist back then, read here). So when you find the difference in seconds, between two dates (your $result), and uses this span as a timestamp (inside your gmdate() function), the output will be the Unix epoch plus these seconds. And that's why we'll have an extra 1970 years, 1 month and 1 day.

Actually, we're making a 'mistake' when we use the time difference as a timestamp, because it's not. But that can be corrected by subtracting the Unix epoch, like I did in the function in this thread.

 

We should be able to subtract the Unix epoch in your example too, just give me a minute..

[thebadbad]

I think this should work. I've divided your code, and subtracted 1 day from the actual output of days (like in my function):

 

<?php
$start = strtotime($row["dateTime"]);
$end = strtotime($row["dateTimeFin"]);

$result = ($end - $start);

$conv=(gmdate('d', $result) - 1).' days, '.gmdate('H', $result).' hours and '.gmdate('i', $result).' minutes.';

echo ($conv);
//x days, x hours and x minutes.
?>

[HughbertD]

Thanks so much!

 

Explanation makes sense to!

 

I take it the topic solved button is still down?

 

Thanks again!