How to Calculate the Number of Days Between Two Dates

// new Date("dateString") is browser-dependent and discouraged, so we'll write// a simple parse function for U.S. date format (which does no error checking)function parseDate(str) {    var mdy = str.split('/');    return new Date(mdy[2], mdy[0]-1, mdy[1]);}
function datediff(first, second) {    // Take the difference between the dates and divide by milliseconds per day.    // Round to nearest whole number to deal with DST.    return Math.round((second-first)/(1000*60*60*24));}
alert(datediff(parseDate(first.value), parseDate(second.value)));

<input id="first" value="1/1/2000"/><input id="second" value="1/1/2001"/>

Android calculate days between two dates

Your code for generating date object:

Date date = new Date("2/3/2017"); //deprecated

You are getting 28 days as answer because according to Date(String) constructor it is thinking day = 3,month = 2 and year = 2017

You can convert String to Date as follows:

String dateStr = "2/3/2017";
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date date = sdf.parse(dateStr);

Use above template to make your Date object. Then use below code for calculating days in between two dates. Hope this clear the thing.

It can de done as follows:

long diff = endDateValue.getTime() - startDateValue.getTime();
System.out.println ("Days: " + TimeUnit.DAYS.convert(diff, TimeUnit.MILLISECONDS));

Please check link

If you use Joda Time it is much more simple:

int days = Days.daysBetween(date1, date2).getDays();

Please check JodaTime

How to use JodaTime in Java Project

How to calculate the number of days between two dates?

const oneDay = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds
const firstDate = new Date(2008, 1, 12);
const secondDate = new Date(2008, 1, 22);

const diffDays = Math.round(Math.abs((firstDate - secondDate) / oneDay));

Finding the number of days between two dates

$now = time(); // or your date as well
$your_date = strtotime("2010-01-31");
$datediff = $now - $your_date;

echo round($datediff / (60 * 60 * 24));

How to finding the number of days between two days of the week?

Your task doesn't seem to require date functions at all. A simple lookup array will suffice.

1. Subtract the starting day's integer value from the ending day's integer.
2. If the difference would be zero or less, add 7 to always return the correct, positive day count.

Code: (Demo)

function daysUntil($start, $end) {
    $lookup = [
        'Sunday' => 0,
        'Monday' => 1,
        'Tuesday' => 2,
        'Wednesday' => 3,
        'Thursday' => 4,
        'Friday' => 5,
        'Saturday' => 6
    ];
    $days = $lookup[$end] - $lookup[$start] + ($lookup[$end] <= $lookup[$start] ? 7 : 0);
    return "{$days} days from {$start} to {$end}\n";
}

echo daysUntil('Wednesday', 'Saturday');  // Thursday, Friday, Saturday
echo daysUntil('Monday', 'Friday');       // Tuesday, Wednesday, Thursday, Friday
echo daysUntil('Thursday', 'Thursday');   // [assumed next week]
echo daysUntil('Friday', 'Monday');       // Saturday, Sunday, Monday
echo daysUntil('Saturday', 'Sunday');     // Sunday
echo daysUntil('Sunday', 'Saturday');     // Monday, Tuesday, Wednesday, Thursday, Friday, Saturday
echo daysUntil('Sunday', 'Wednesday');    // Monday, Tuesday, Wednesday

Output:

3 days from Wednesday to Saturday
4 days from Monday to Friday
7 days from Thursday to Thursday
3 days from Friday to Monday
1 days from Saturday to Sunday
6 days from Sunday to Saturday
3 days from Sunday to Wednesday

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Or you can replace the lookup array with 4 function calls and achieve the same outcome: (Demo)

function daysUntil($start, $end) {
    $days = date('w', strtotime($end)) - date('w', strtotime($start));
    $days += $days < 1 ? 7 : 0;
    return "{$days} days from {$start} to {$end}\n";
}

Calculate number of days between two dates?

Your program seems to work as intended. I'm getting 45.55 hours. Have you tried to run it locally?

Playground time is fixed, time.Now() will give you 2009-11-10 23:00:00 +0000 UTC always.

Calculating number of days between two dates

you do not need DateDif for just number of days. Just subtract the two numbers and format the output as general.

=IF(B2<>"",IF(C2<>"",C2-B2,today()-B2),"")

How to calculate the difference between two dates using PHP?

Use this for legacy code (PHP < 5.3). For up to date solution see jurka's answer below

You can use strtotime() to convert two dates to unix time and then calculate the number of seconds between them. From this it's rather easy to calculate different time periods.

$date1 = "2007-03-24";
$date2 = "2009-06-26";

$diff = abs(strtotime($date2) - strtotime($date1));

$years = floor($diff / (365*60*60*24));
$months = floor(($diff - $years * 365*60*60*24) / (30*60*60*24));
$days = floor(($diff - $years * 365*60*60*24 - $months*30*60*60*24)/ (60*60*24));

printf("%d years, %d months, %d days\n", $years, $months, $days);

Edit: Obviously the preferred way of doing this is like described by jurka below. My code is generally only recommended if you don't have PHP 5.3 or better.

Several people in the comments have pointed out that the code above is only an approximation. I still believe that for most purposes that's fine, since the usage of a range is more to provide a sense of how much time has passed or remains rather than to provide precision - if you want to do that, just output the date.

Despite all that, I've decided to address the complaints. If you truly need an exact range but haven't got access to PHP 5.3, use the code below (it should work in PHP 4 as well). This is a direct port of the code that PHP uses internally to calculate ranges, with the exception that it doesn't take daylight savings time into account. That means that it's off by an hour at most, but except for that it should be correct.

<?php

/**
 * Calculate differences between two dates with precise semantics. Based on PHPs DateTime::diff()
 * implementation by Derick Rethans. Ported to PHP by Emil H, 2011-05-02. No rights reserved.
 * 
 * See here for original code:
 * http://svn.php.net/viewvc/php/php-src/trunk/ext/date/lib/tm2unixtime.c?revision=302890&view=markup
 * http://svn.php.net/viewvc/php/php-src/trunk/ext/date/lib/interval.c?revision=298973&view=markup
 */

function _date_range_limit($start, $end, $adj, $a, $b, $result)
{
    if ($result[$a] < $start) {
        $result[$b] -= intval(($start - $result[$a] - 1) / $adj) + 1;
        $result[$a] += $adj * intval(($start - $result[$a] - 1) / $adj + 1);
    }

    if ($result[$a] >= $end) {
        $result[$b] += intval($result[$a] / $adj);
        $result[$a] -= $adj * intval($result[$a] / $adj);
    }

    return $result;
}

function _date_range_limit_days($base, $result)
{
    $days_in_month_leap = array(31, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
    $days_in_month = array(31, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

    _date_range_limit(1, 13, 12, "m", "y", &$base);

    $year = $base["y"];
    $month = $base["m"];

    if (!$result["invert"]) {
        while ($result["d"] < 0) {
            $month--;
            if ($month < 1) {
                $month += 12;
                $year--;
            }

            $leapyear = $year % 400 == 0 || ($year % 100 != 0 && $year % 4 == 0);
            $days = $leapyear ? $days_in_month_leap[$month] : $days_in_month[$month];

            $result["d"] += $days;
            $result["m"]--;
        }
    } else {
        while ($result["d"] < 0) {
            $leapyear = $year % 400 == 0 || ($year % 100 != 0 && $year % 4 == 0);
            $days = $leapyear ? $days_in_month_leap[$month] : $days_in_month[$month];

            $result["d"] += $days;
            $result["m"]--;

            $month++;
            if ($month > 12) {
                $month -= 12;
                $year++;
            }
        }
    }

    return $result;
}

function _date_normalize($base, $result)
{
    $result = _date_range_limit(0, 60, 60, "s", "i", $result);
    $result = _date_range_limit(0, 60, 60, "i", "h", $result);
    $result = _date_range_limit(0, 24, 24, "h", "d", $result);
    $result = _date_range_limit(0, 12, 12, "m", "y", $result);

    $result = _date_range_limit_days(&$base, &$result);

    $result = _date_range_limit(0, 12, 12, "m", "y", $result);

    return $result;
}

/**
 * Accepts two unix timestamps.
 */
function _date_diff($one, $two)
{
    $invert = false;
    if ($one > $two) {
        list($one, $two) = array($two, $one);
        $invert = true;
    }

    $key = array("y", "m", "d", "h", "i", "s");
    $a = array_combine($key, array_map("intval", explode(" ", date("Y m d H i s", $one))));
    $b = array_combine($key, array_map("intval", explode(" ", date("Y m d H i s", $two))));

    $result = array();
    $result["y"] = $b["y"] - $a["y"];
    $result["m"] = $b["m"] - $a["m"];
    $result["d"] = $b["d"] - $a["d"];
    $result["h"] = $b["h"] - $a["h"];
    $result["i"] = $b["i"] - $a["i"];
    $result["s"] = $b["s"] - $a["s"];
    $result["invert"] = $invert ? 1 : 0;
    $result["days"] = intval(abs(($one - $two)/86400));

    if ($invert) {
        _date_normalize(&$a, &$result);
    } else {
        _date_normalize(&$b, &$result);
    }

    return $result;
}

$date = "1986-11-10 19:37:22";

print_r(_date_diff(strtotime($date), time()));
print_r(_date_diff(time(), strtotime($date)));

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