Date math

legal-medium

Why is it that if the variable $form[age2] is greater than 33 that the following variable "$date2" returns a value of -1

$date2= mktime(0,0,0, date('m') ,date('d'), date('Y')-$form[age2]);

I am sure it has someting to do with the way I am trying to calculate with mktime

Thanks in advance

volleytotal_ch

have you echoed the variable? what was the result?

legal-medium

"if the variable $form[age2] is greater than 33"

"the following variable "$date2" returns a value of -1"

$date2= mktime(0,0,0, date('m') ,date('d'), date('Y')-$form[age2]);

So yes I did echo, that is not the problem, the problen is the coversion in side mktime();

Sphynx

well really date("Y") is a string. so you can get some funky results if you try to do a mathematical function on that.

try using intval(), which should return the integer value of date("Y").

$date2= mktime(0,0,0, date('m') ,date('d'), intval(date('Y'))-$form[age2]);

milind24

Try to read following : or read help of mktime() in manual

However, there is one thing you may want to take note
of...namely INTEGER limitations. Apparently the mktime() function
returns the UNIX time conversion of a date where the values
represent seconds since Jan 1, 1970, and are positive or
negative depending on whether the date appears before or after
1970. Due to the MAX_INT (LONG?) size, dates can only be
represented as far back as 1902 (- MAX) and as far forward as
2037 (+ MAX).

Also, the addition of any field that might exceed the max_int
limitation itself will cause an invalid calculation and reset the date
to Dec 31, 1969 (Unix time of -1).

EX:
$day_shift = 36524;
$stmp = mktime(0,0,0,1,$day_shift,1903);

it will produce output -1 .

why ? because

// 36524 days == 3155673600 secs)
In this case, the 3155673600 shift is too large for the mktime() function to compute, so you end up with -1. However, if you do your same shift in smaller increments (say 10,000 days at a time) the calculations will work and you'll be fine 😉