Datetime-obtenir mardi prochain

Cela devrait faire l'affaire:

static DateTime GetNextWeekday(DayOfWeek day)
{
    DateTime result = DateTime.Now.AddDays(1);
    while( result.DayOfWeek != day )
        result = result.AddDays(1);
    return result;
}

DateTime nextTuesday = DateTime.Today.AddDays(((int)DateTime.Today.DayOfWeek - (int)DayOfWeek.Tuesday) + 7);

Il existe des solutions moins verbeuses et plus intelligentes/élégantes à ce problème, mais la fonction C# suivante fonctionne très bien pour un certain nombre de situations.

/// <summary>
/// Find the closest weekday to the given date
/// </summary>
/// <param name="includeStartDate">if the supplied date is on the specified day of the week, return that date or continue to the next date</param>
/// <param name="searchForward">search forward or backward from the supplied date. if a null parameter is given, the closest weekday (ie in either direction) is returned</param>
public static DateTime ClosestWeekDay(this DateTime date, DayOfWeek weekday, bool includeStartDate = true, bool? searchForward=true)
{
    if (!searchForward.HasValue && !includeStartDate) 
    {
        throw new ArgumentException("if searching in both directions, start date must be a valid result");
    }
    var day = date.DayOfWeek;
    int add = ((int)weekday - (int)day);
    if (searchForward.HasValue)
    {
        if (add < 0 && searchForward.Value)
        {
            add += 7;
        }
        else if (add > 0 && !searchForward.Value)
        {
            add -= 7;
        }
        else if (add == 0 && !includeStartDate)
        {
            add = searchForward.Value ? 7 : -7;
        }
    }
    else if (add < -3) 
    {
        add += 7; 
    }
    else if (add > 3)
    {
        add -= 7;
    }
    return date.AddDays(add);
}

DateTime nexttuesday=DateTime.Today.AddDays(1);

while(nexttuesday.DayOfWeek!=DayOfWeek.Tuesday)
   nexttuesday = nexttuesday.AddDays(1);

@Jon Skeet bonne réponse.

Pour le jour précédent:

private DateTime GetPrevWeekday(DateTime start, DayOfWeek day) {
    // The (... - 7) % 7 ensures we end up with a value in the range [0, 6]
    int daysToRemove = ((int) day - (int) start.DayOfWeek - 7) % 7;
    return start.AddDays(daysToRemove);
}

Merci!!

Maintenant dans la saveur oneliner - au cas où vous auriez besoin de le passer en paramètre dans un mécanisme.

DateTime.Now.AddDays(((int)yourDate.DayOfWeek - (int)DateTime.Now.DayOfWeek + 7) % 7).Day

Dans ce cas spécifique:

DateTime.Now.AddDays(((int)DayOfWeek.Tuesday - (int)DateTime.Now.DayOfWeek + 7) % 7).Day

Il pourrait Être une extension aussi, tout dépend

public static class DateTimeExtensions
{
    public static IEnumerable<DateTime> Next(this DateTime date, DayOfWeek day)
    {
        // This loop feels expensive and useless, but the point is IEnumerable
        while(true)
        {
            if (date.DayOfWeek == day)
            {
                yield return date;
            }
            date = date.AddDays(1);
        }
    }
}

Utilisation

    var today = DateTime.Today;
    foreach(var monday in today.Next(DayOfWeek.Monday))
    {
        Console.WriteLine(monday);
        Console.ReadKey();
    }

Objectif C Version:

+(NSInteger) daysUntilNextWeekday: (NSDate*)startDate withTargetWeekday: (NSInteger) targetWeekday
{
    NSInteger startWeekday = [[NSCalendar currentCalendar] component:NSCalendarUnitWeekday fromDate:startDate];
    return (targetWeekday - startWeekday + 7) % 7;
}