How can I get the next particular day after a month in c#, for example if today is Monday I need to get the first Monday after 1 month from now, but in more generic way, for example if today is 17/11/2021 which is Wednesday I need to get the first Wednesday after a month from now I am using this function but it will return for next week and not next month
public static DateTime GetNextWeekday(DateTime start, DayOfWeek day)
{
// The (... 7) % 7 ensures we end up with a value in the range [0, 6]
int daysToAdd = ((int)day - (int)start.DayOfWeek 7) % 7;
return start.AddDays(daysToAdd);
}
CodePudding user response:
Typical month has 30
or 31
days, however, the next same day of week will be after either 28
(4 * 7
) or 35
(5 * 7
) days. We need a compromise. Let for February
add 28
days and for all the other months add 35
days:
public static DateTime GetSameDayAfterMonth(DateTime start) =>
start.AddDays((start.AddMonths(1) - start).TotalDays < 30 ? 28 : 35);
Sure, you can elaborate other rules: say, when after adding 28
days we are still in the same month (1 May 28 days == 29 May
) we should add 35
:
public static DateTime GetSameDayAfterMonth(DateTime start) =>
start.AddDays(start.Month == start.AddDays(28).Month ? 35 : 28);
CodePudding user response:
Add a month, instead of a week to the start date:
public static DateTime GetSameDayAfterMonth(DateTime start)
{
var compare = start.AddMonths(1);
// The % 7 ensures we end up with a value in the range [0, 6]
int daysToAdd = ((int)start.DayOfWeek - (int)compare.DayOfWeek) % 7;
return compare.AddDays(daysToAdd);
}
Example:
var dayInNextMonth = GetSameDayAfterMonth(DateTime.Parse("2021-11-17")); // 2021-12-15
var weekday = dayInNextMonth.DayOfWeek; // Wednesday