How do I get the last day of a month?

Question

How can I find the last day of the month in C#?

For example, if I have the date 03/08/1980, how do I get the last day of month 8 (in this case 31)?

Answer 1

The last day of the month you get like this, which returns 31:

DateTime.DaysInMonth(1980, 08);

Answer 2

var lastDayOfMonth = DateTime.DaysInMonth(date.Year, date.Month);

Answer 3

If you want the date, given a month and a year, this seems about right:

public static DateTime GetLastDayOfMonth(this DateTime dateTime)
{
    return new DateTime(dateTime.Year, dateTime.Month, DateTime.DaysInMonth(dateTime.Year, dateTime.Month));
}

Answer 4

Substract a day from the first of next month:

DateTime lastDay = new DateTime(MyDate.Year,MyDate.Month+1,1).AddDays(-1);

Also, in case you need it to work for December too:

DateTime lastDay = new DateTime(MyDate.Year,MyDate.Month,1).AddMonths(1).AddDays(-1);

Answer 5

You can find the last date of any month by this code:

var now = DateTime.Now;
var startOfMonth = new DateTime(now.Year, now.Month, 1);
var DaysInMonth = DateTime.DaysInMonth(now.Year, now.Month);
var lastDay = new DateTime(now.Year, now.Month, DaysInMonth);

Answer 6

You can find the last day of the month by a single line of code:

int maxdt = (new DateTime(dtfrom.Year, dtfrom.Month, 1).AddMonths(1).AddDays(-1)).Day;

Answer 7

From DateTimePicker:

First date:

DateTime first_date = new DateTime(DateTimePicker.Value.Year, DateTimePicker.Value.Month, 1);

Last date:

DateTime last_date = new DateTime(DateTimePicker.Value.Year, DateTimePicker.Value.Month, DateTime.DaysInMonth(DateTimePicker.Value.Year, DateTimePicker.Value.Month));

Answer 8

// Use any date you want, for the purpose of this example we use 1980-08-03.
var myDate = new DateTime(1980,8,3);
var lastDayOfMonth = new DateTime(myDate.Year, myDate.Month, DateTime.DaysInMonth(myDate.Year, myDate.Month));

Answer 9

To get last day of a month in a specific calendar - and in an extension method -:

public static int DaysInMonthBy(this DateTime src, Calendar calendar)
{
    var year = calendar.GetYear(src);                   // year of src in your calendar
    var month = calendar.GetMonth(src);                 // month of src in your calendar
    var lastDay = calendar.GetDaysInMonth(year, month); // days in month means last day of that month in your calendar
    return lastDay;
}

Answer 10

This will display the last date of the next month. You can add the month of the year you want to return by adding or substracting it from AddMonths(x)

DateTime.Now.AddMonths(2).AddDays(-DateTime.Now.Day)

Answer 11

This formula reflects @RHSeeger's thought as a simple solution to get (in this example) the last day of the 3rd month (month of date in cell A1 + 4 with the first day of that month minus 1 day):

=DATE(YEAR(A1);MONTH(A1)+4;1)-1

Very precise, inclusive February's in leap years :)

Answer 12

example on 05/07/2021

DateTime.Now.Day;

Result: 5

DateTime.Now.AddMonths(+1).AddDays(-DateTime.Now.Day).ToString("yyyy-MM-dd");

result: 2021/07/31

Answer 13

Another way to get end date:

    private static DateTime GetMonthEndDate(DateTime date)
    {
        DateTime endDate = date;
        int endDateMonth = endDate.Month;

        while (endDateMonth == endDate.Month)
            endDate = endDate.AddDays(1);

        endDate = endDate.AddDays(-1);

        return endDate;
    }

Answer 14

I don't know C# but, if it turns out there's not a convenient API way to get it, one of the ways you can do so is by following the logic:

today -> +1 month -> set day of month to 1 -> -1 day

Of course, that assumes you have date math of that type.