Get the number of weeks between 2 strings - php

Question

I've been trying to figure out how to output the amount of weeks between 2 dates using strings given to my server.
Every thread I found that has potentially the same problem as me is using datetime() which I'm not extremely familiar with, and I believe uses a different structure than me.
Anyways, I can't figure this out and I've been trying for a couple of hours.
These are the strings I need to feed into the function:
From: "8/3/2015" to: "07/27/2015"
Note, the from string will change each week according to the monday from every week. Also, there are several To dates, and there will be a new one each week.
It would also be a lovely feature if it converted to months and years if it applies.
UPDATE
This is what I came up with, with the help of phplovers answer. This should successfully give you back the amount of days, unless its more than 7, then it would give you weeks, then months, then years.
Pardon the messiness.
$from = date_create($startDate);
$to = date_create($endDate);
$interval = date_diff($from, $to);
if( $interval->format("%a") % 7 == 0 ){
$amt = ($interval->format("%a") / 7);
if($amt == 1) {
$display = $amt . " Week";
} else {
if($amt >= 4) {
$amt2 = $interval->format("%m");
if($amt2 == 1) {
$display = $amt2 . " Month";
} else {
$display = $amt2 . " Months";
$amt3 = $interval->format("%y");
if($amt3 == 1) {
$display = $amt3 . " Year";
} else {
$display = $amt3 . " Years";
}
}
} else {
$display = $amt . " Weeks";
}
}
} else {
$display = ($interval->format("%a")) . " Days";
}
You'd just echo $display anywhere you needed the time difference.

Answer 1

I have used this in some earlier project. Hope this might help you.
function datediffInWeeks($date1, $date2)
{
if($date1 > $date2) return datediffInWeeks($date2, $date1);
$first = DateTime::createFromFormat('d/m/Y', $date1);
$second = DateTime::createFromFormat('d/m/Y', $date2);
return floor($first->diff($second)->days/7);
}
var_dump(datediffInWeeks('8/3/2015', '7/27/2015'));

Answer 2

First thing you need to do is convert the strings to something that is easy to work with. Unixtime is probably the easiest when you are doing comparisons. Unixtime is the number of seconds since the Unix Epoch (January 1, 1970). Here is what I would do:
$date_from = strtotime( '8/3/2015' ) // Change to your input
$date_to = strtotime( '07/27/2015' ) // Change to your input
$difference = $date_to - $date_from; // The seconds between these times
$seconds_in_minute = 60;
$seconds_in_hour = $seconds_in_minute * 60;
$seconds_in_day = $seconds_in_hour * 24;
$seconds_in_week = $seconds_in_day * 7;
$seconds_in_month = $seconds_in_day * 30;
$seconds_in_year = $seconds_in_day * 365;
Each of these variables store how many seconds are in the specific timeframe. What you can do is check agains these variables using some basic math.
$years = floor( $difference / $seconds_in_year );
$months = floor( ($difference - $years * $seconds_in_year ) / ( $seconds_in_month ) );
$days = floor( ( $difference - $years * $seconds_in_year - $months * $seconds_in_month ) / ( $seconds_in_day ) );
This is a long form example of what is happening in the date_diff() function in PHP. However, that function is only available post PHP 5.3, so if you are using an older version of PHP you can try this method.

Answer 3

As MrT stated, using date() functions you can achieve this easily:
$from = date_create("07/27/2015");
$to = date_create("08/03/2015");
$interval = date_diff($from, $to);
echo $interval->format("%a"); // %a will give difference in days
For more about formatting this take a look at date_diff()

Answer 4

Visit: http://php.net/manual/en/datetime.diff.php
$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days');

Answer 5

There is an awesome PHP extension for this thing.Its called carbon.
Specifically, for your given task you can do the following(I am skipping the code of importing and stuff):
$dt = Carbon::create(2014, 1, 1);
$dt2 = Carbon::create(2014, 12, 31);
echo $dt->diffInWeeks($dt2);
The above function will give you your answer.
Also, you can use their createFromFormat() method to create carbon objects of date
Link:
http://carbon.nesbot.com/

Answer 6

The 'W' date format fetches the week of the year that the date falls in.
$from = date('W', strtotime('07/27/2015') ) ;
$to = date('W', strtotime('8/3/2015') ) ;
//$from and $to now have the week of the year that their dates fall in.
//This simple math produces the the number of weeks from one date to the next.
$numOfWeeks = $to - $from;