How to calculate number of days between two dates?
Here is a quick and dirty implementation of datediff
, as a proof of concept to solve the problem as presented in the question. It relies on the fact that you can get the elapsed milliseconds between two dates by subtracting them, which coerces them into their primitive number value (milliseconds since the start of 1970).
/**
* Take the difference between the dates and divide by milliseconds per day.
* Round to nearest whole number to deal with DST.
*/
function datediff(first, second) {
return Math.round((second - first) / (1000 * 60 * 60 * 24));
}
/**
* 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]);
}
alert(datediff(parseDate(first.value), parseDate(second.value)));
<input id="first" value="1/1/2000"/>
<input id="second" value="1/1/2001"/>
Get calendar days between two dates
You don't need string manipulation to get a DateTime without the time part, just use DateTime.Date.
To get the time span between two dates, just subtract one from the other. Subtracting one date from another returns a TimeSpan object whose Days property is the difference in full dates.
All you need to do is :
Dim days As Integer =(date2.Date-date1.Date).Days
This way you avoid generating and parsing temporary strings.
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.
Excel - count days between two dates per year
Put this in C2 and copy over:
=MIN(DATE(C1,12,31),$B$2)-MAX(DATE(C1,1,1),$A$2)
Flutter: Find the number of days between two dates
You can use the difference
method provide by DateTime
class
//the birthday's date
final birthday = DateTime(1967, 10, 12);
final date2 = DateTime.now();
final difference = date2.difference(birthday).inDays;
UPDATE
Since many of you reported there is a bug with this solution and to avoid more mistakes, I'll add here the correct solution made by @MarcG, all the credits to him.
int daysBetween(DateTime from, DateTime to) {
from = DateTime(from.year, from.month, from.day);
to = DateTime(to.year, to.month, to.day);
return (to.difference(from).inHours / 24).round();
}
//the birthday's date
final birthday = DateTime(1967, 10, 12);
final date2 = DateTime.now();
final difference = daysBetween(birthday, date2);
This is the original answer with full explanation: https://stackoverflow.com/a/67679455/666221
Days between two dates?
Assuming you’ve literally got two date objects, you can subtract one from the other and query the resulting timedelta
object for the number of days:
>>> from datetime import date
>>> a = date(2011,11,24)
>>> b = date(2011,11,17)
>>> a-b
datetime.timedelta(7)
>>> (a-b).days
7
And it works with datetimes too — I think it rounds down to the nearest day:
>>> from datetime import datetime
>>> a = datetime(2011,11,24,0,0,0)
>>> b = datetime(2011,11,17,23,59,59)
>>> a-b
datetime.timedelta(6, 1)
>>> (a-b).days
6
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),"")
count the number of days between two dates per year
Here's one approach using tidyverse
and lubridate
.
First, separate the rows by calendar year, to use to measure the number of days for each year. Each row will include dates to be counted in each calendar year, starting with January 1st and ending with December 31st if overlapping multiple years. Then, it is easy to calculate the number of days in a given year.
The results from this example are slightly different than what I have. Year 2016 is a leap year and has 366 days. If the number of days are not inclusive of either start or end dates, you would get a different answer.
library(tidyverse)
library(lubridate)
df %>%
mutate(date_int = interval(start, end),
year = map2(year(start), year(end), seq)) %>%
unnest(year) %>%
mutate(year_int = interval(as.Date(paste0(year, '-01-01')), as.Date(paste0(year, '-12-31'))),
year_sect = intersect(date_int, year_int),
start_new = as.Date(int_start(year_sect)),
end_new = as.Date(int_end(year_sect))) %>%
select(id, start_new, end_new) %>%
mutate(year = year(start_new),
days = as.numeric(end_new - start_new)) %>%
right_join(df) %>%
pivot_wider(id_cols = c(id, start, end), names_from = year, values_from = days, names_prefix = "year_", values_fill = list(days = 0)) %>%
mutate(days_number = reduce(select(., starts_with("year_")), `+`))
Output
id start end year_2015 year_2016 days_number
<dbl> <date> <date> <dbl> <dbl> <dbl>
1 1 2015-01-01 2016-12-31 364 365 729
2 2 2016-01-01 2016-12-31 0 365 365
3 3 2015-07-01 2016-12-31 183 365 548
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