[Skunkworks] PHP: dates between dates code review

25 Nov 2009

      I have been pulling out my hair for the last few hours...

Given two dates in whichever format, e.g. 2009-10-06 and November 12, 2009,
which is the best logical approach here to get all dates in between those
two dates?

I was thinking of converting the received dates into timestamps, then using
mktime to add one day to the older timestamp till i get to the new one, but
a small voice tells me there is a better way. Any ideas?

Here is the code I am using.

<?php

/**
 * Get the days between two dates and return those actual dates in an array
*/
function getDaysBetweenDates($startDate, $endDate){
    //initialize array that will get returned
    $daysBetweenDatesArray = array();

    //attempt to convert the received dates into timestamps
    $startDateTimestamp = strtotime($startDate);
    $endDateTimestamp = strtotime($endDate);

    /*TODO: Problem 1: even if the received dates are bogus, strtotime()
will convert them into
    sane timestamps, which might pass the checkdate() validation below
    */

    //check that the received values are valid
    if (!checkdate(date('n',$startDateTimestamp),
date('j',$startDateTimestamp), date('Y',$startDateTimestamp))) {
        //do some error handling here
        return false;
    }

    if (!checkdate(date('n',$endDateTimestamp), date('j',$endDateTimestamp),
date('Y',$endDateTimestamp))) {
        //do some error handling here
        return false;
    }

    //dates received are probably valid

    /*
    Logic 1: One day has (24*60*60) seconds, therefore, if I can get the
number of 86400 seconds between those two days,
    I can get those actual dates. Havent used this method

    Logic 2: Use mktime to add One to the start date, then increment
$startDateTimestamp with 86400, i.e. the number of seconds in one day
    and loop it untill $startDateTimestamp is less than or equal to
$endDateTimestamp.
    */

    //variable to count the number of times the loop has run, will be used
as index in the $daysBetweenDatesArray array
    $loopCounter = 1;

    //variable to store the dates found in between, not really necessary,
the dates found could be put directly in the array
    $dateInBetweenTimestamp = '';

    //assume startDate is included, put it as first element in array
    $daysBetweenDatesArray[0] = date('j-n-Y', $startDateTimestamp);

    while ($startDateTimestamp <= $endDateTimestamp) {
        //in order to use mktime, we will need seconds, minutes, hours, day,
month and year for each date
        $startDateSecond = date('s',$startDateTimestamp);
        $startDateMinute = date('i',$startDateTimestamp);
        $startDateHour = date('G',$startDateTimestamp);
        $startDateDay = date('j',$startDateTimestamp);
        $startDateMonth = date('n',$startDateTimestamp);
        $startDateYear = date('Y',$startDateTimestamp);

        $dateInBetweenTimestamp = mktime($startDateHour, $startDateMinute,
$startDateSecond, $startDateMonth, $startDateDay+1, $startDateYear);
        $daysBetweenDatesArray[$loopCounter] = date('j-n-Y',
$dateInBetweenTimestamp);

        //increment loop counter
        $loopCounter++;

        //increment $startDateTimestamp
        $startDateTimestamp = $startDateTimestamp + 86400;
    }

    return $daysBetweenDatesArray;
}

?>

How to use:
<?php
$datesInBetween = getDaysBetweenDates('2009-01-01', '2009-01-30');
print_r($datesInBetween)    ;
?>

[Skunkworks] PHP: dates between dates code review

Peter Karunyu