Simple date calculations

[joseph_adams1]

Hi all,

I have two DATE fields in database,

Date_From
Date_To

I wanted to find the number of days separating them.

I have two possible ideas:

1. I know that date("z") retuns the number of days since the start of the year, could I not put a date into this, so it would tell me how many days have passed since 1st Feb for example?

2.

$daysPassed = 0;
while ($Date_From <= $Date_To)
{
   $Date_From = $Date_From + 86400;
   $daysPassed = $daysPassed + 1;
}
?>

I thought I would try this, but I got nothing (not surprised) but is this possible?

I just thought of something else...

there is an option in date() to return the number of seconds since midnight 1970. Could I put a date into this? Find out how many seconds have passed till a certain date, then calculate days passed from that?

[tekky]

just do something like this
(assuming you are using timestamps)

function days_between($date_from, $date_to)
{
     $d1 = $mktime(0,0,0,date("m",$date_from),date("j",$date_from),date("Y",$date_from)); //midnite of date_from
     $d2 = $mktime(0,0,0,date("m",$date_to),date("j",$date_to),date("Y",$date_to)); //midnite of date_to
     return ($d2 - $d1) / 86400; //difference in seconds between days divided by 86400 (seconds in day) gives you difference in days
}

[timj]

That sounds kind of complicated to me.
You said that you get the dates from a database.
Can't you just do the following:
select date_to-date_from from...;
The database (if it knows SQL) will calculate the difference between the dates as the number of days between the two days (if you eliminate the decimal part). In oracle, you might want to specify
trunc(date_to)-trunc(date_from) because the trunc( ) function will eliminate the "time" out of the timestamp, only keeping the date (eg a roundoff to the start of the day).

[tekky]

that could work too 🙂 but, for PHP answer... 3 lines of code aint bad 😉