PHP days difference calculation error

Question

I have some PHP code to calculate the number of days between two specific dates. The difference should not count Sundays and Saturdays. Also, I have an array of dates, which includes holidays, which also need to be skipped.

I gave the starting date as 01-05-2015 and ending date as 01-06-2015. I gave the entire days in the month of may as array. Thus the difference should be 1 day. But I am getting the output as 7. What is the problem? Here is the code.

function dateRange($first, $last) {
    $dates = array();
    $current = strtotime($first);
    $now = $current;
    $last = strtotime($last);
    while( $current <= $last ) {
        if (date('w', $current) != 0){
            $dates[] = date('d-m-Y', $current);
        }
        $current = strtotime('+1 day', $current);
    }
    unset($dates[0]);
    return $dates;
}


$datea = "01-05-2015";
$date = "01-06-2015";
$hdsarray = array("1-05-2015","2-05-2015","4-05-2015","5-05-2015","7-05-2015","8-05-2015","9-05-2015","11-05-2015","12-05-2015","14-05-2015","15-05-2015","16-05-2015","18-05-2015","19-05-2015","21-05-2015","22-05-2015","23-05-2015","25-05-2015","26-05-2015","28-05-2015","29-05-2015","30-05-2015");

$datesarray = dateRange($datea, $date);
$result = array_diff($hdsarray,$datesarray);
$date_diff = sizeof($result);

echo $date_diff;

Answer 1

The only problem I can see is in the usage of array_diff, It actually includes the sat and sun which is excluded by dateRange function, if not found in holidays list.

Instead, you can pass your holiday dates in dateRange function, and filter over there.

function dateRange($first, $last, $excludeDates) {
    $dates = array();
    $current = strtotime($first);
    $now = $current;
    $last = strtotime($last);
    while( $current <= $last ) {
        if (date('w', $current) != 0 && date('w', $current) != 6 && !in_array(date('j-m-Y', $current), $excludeDates)){
            $dates[] = date('d-m-Y', $current);
        }
        $current = strtotime('+1 day', $current);
    }
    return $dates;
}

$datea = "01-05-2015";
$date = "01-06-2015";
$hdsarray = array("1-05-2015","2-05-2015","4-05-2015","5-05-2015","7-05-2015","8-05-2015","9-05-2015","11-05-2015","12-05-2015","14-05-2015","15-05-2015","16-05-2015","18-05-2015","19-05-2015","21-05-2015","22-05-2015","23-05-2015","25-05-2015","26-05-2015","28-05-2015","29-05-2015","30-05-2015");
$datesarray = dateRange($datea, $date, $hdsarray);print_r($datesarray);

Result:

Array
(
    [0] => 06-05-2015
    [1] => 13-05-2015
    [2] => 20-05-2015
    [3] => 27-05-2015
    [4] => 01-06-2015
)

All the 5 dates come in the result, are not sat, sun, and also not there in holidays list.

Answer 2

It seems that there are several problems here. First, as pointed out by others the condition:

if (date('w', $current) != 0){

only checks for Sundays, if it should also include Saturday's it should be:

if (date('w', $current) != 0 && date('w', $current) != 6){

Secondly, it seems that the $hdsarray array does not contain all of the days in May. It seems that all of the Wednesdays are missing.

The third issue is that you are using array_diff on two arrays, one containing Dates and the other ones containing Strings. From the documentation:

Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. In words: when the string representation is the same.

In your $hdsarray you are using "1-05-2015" to denote the first day of the month, while:

 echo date('d-m-Y', strtotime("1-05-2015"));

results in "01-05-2015". You will need to add an additional 0 in $hdsarray for these dates or work with dates as well.

Last but not least, the current algorithm will not work correctly if the $hdsarray contains dates for a Saturday or Sunday, the result of array_diff will still contain these dates. Since you want to filter the result of daterange the array_filter function might be more suitable.

Answer 3

Despite an answer has already been provided, here is a little snippet with a class handling everything for you:

<?php

class dateRange {
    protected $start, $end, $daysToExclude, $datesToExclude;

    function __construct($dateStart, $dateEnd, $daysToExclude, $datesToExclude) {
        $this->start            =   $dateStart;
        $this->end              =   $dateEnd;
        $this->daysToExclude    =   $daysToExclude;
        $this->datesToExclude   =   $this->fixFormat($datesToExclude);
    }

    public function getRangeLength ($callback = null) {
        $tmp    =   array();

        $now    =   strtotime($this->start);
        $to     =   strtotime($this->end);

        while ( $now <= $to ) {
            if (!in_array(date("w", $now), $this->daysToExclude)) {
                $tmp[] = date('d-m-Y', $now);
            }
            $now = strtotime('+1 day', $now);
        }

        is_callable($callback) && call_user_func($callback, array_diff($tmp,$this->datesToExclude));

        return count(array_diff($tmp,$this->datesToExclude));
    }

    private function fixFormat($el) {
        if (!is_array($el)) {
            return false;
        }
        else {
            foreach ($el as &$value) {
                $value  =   date("d-m-Y",strtotime($value));
            }
            return $el;
        }
    }
}

?>

I decided to keep your current logic (using date_diff), but I thought that, in the future, you may have your boss telling you "You know what? I don't want to have mondays aswell there" so, with the current system, you will have to edit your function manually and, perhaps, you won't remember anymore what you did.

The class above expects four parameters:

• dateStart (d-m-Y format)
• dateEnd (d-m-Y format)
• daysToExclude (array with IDs of the days to exclude -> example array(0,6) to exclude saturdays and sundays).
• datesToExclude (array with the dates to exclude, every format supported).

The class will automatically fix the datesToExclude array format in order to allow you to use date_diff.

Here is an example to use it, following your case:

<?php

    $dateStart      = "01-05-2015";
    $dateEnd        = "01-06-2015";
    $daysToExclude  = array(0,6); 
    $exclusions = array(
                "1-05-2015",
                "2-05-2015",
                "4-05-2015",
                "5-05-2015",
                "7-05-2015",
                "8-05-2015",
                "9-05-2015",
                "11-05-2015",
                "12-05-2015",
                "14-05-2015",
                "15-05-2015",
                "16-05-2015",
                "18-05-2015",
                "19-05-2015",
                "21-05-2015",
                "22-05-2015",
                "23-05-2015",
                "25-05-2015",
                "26-05-2015",
                "28-05-2015",
                "29-05-2015",
                "30-05-2015"
            );
            $dateRange = new dateRange($dateStart, $dateEnd, $daysToExclude, $exclusions);
            echo $dateRange->getRangeLength();
?>

The code above outputs 5.

The function getRangeLength also accepts a callback and will return the array resulting of the date_diff operation, so you can also:

$dateRange->getRangeLength(function($res) {
    echo "Literal output: <br />";
    print_r($res);
    echo "<br />count is: "  . count($res);
});

The above outputs:

Literal output: 
Array ( [3] => 06-05-2015 [8] => 13-05-2015 [13] => 20-05-2015 [18] => 27-05-2015 [21] => 01-06-2015 ) 
count is: 5

So if you later will need to remove mondays too, you will be able to easily do that by changing daysToExclude to array(0,1,6);

Hope this will be helpful to anyone else who will need this, despite a valid answer has already been posted.

Your original problem, in any case, was pretty much related to the array_diff function, which was NOT doing its job because of the fact that the date strings were not compatible, because "1-01-2015" is different from "01-01-2015", unless you first convert BOTH of them to times and then back to dates.

Answer 4

The code is fine (except that $nowis not used at all). The problem is the $hdsarray is wrong:

It should $hdsarray = array("01-05-2015", "02-05-2015", "04-05-2015", "05-05-2015", "07-05-2015", "08-05-2015", "09-05-2015",...);

date('d-m-Y', $current);will always return a leading 0 for all days between 1 and 9.

That's where the difference comes from.