Question

How can I get the date of next Tuesday?

In PHP, it’s as simple as strtotime('next tuesday');.

How can I achieve something similar in .NET

Answer 1

As I’ve mentioned in the comments, there are various things you could mean by “next Tuesday”, but this code gives you “the next Tuesday to occur, or today if it’s already Tuesday”:

DateTime today = DateTime.Today;
// The (... + 7) % 7 ensures we end up with a value in the range [0, 6]
int daysUntilTuesday = ((int) DayOfWeek.Tuesday - (int) today.DayOfWeek + 7) % 7;
DateTime nextTuesday = today.AddDays(daysUntilTuesday);

If you want to give “a week’s time” if it’s already Tuesday, you can use:

// This finds the next Monday (or today if it's Monday) and then adds a day... so the
// result is in the range [1-7]
int daysUntilTuesday = (((int) DayOfWeek.Monday - (int) today.DayOfWeek + 7) % 7) + 1;

… or you could use the original formula, but from tomorrow:

DateTime tomorrow = DateTime.Today.AddDays(1);
// The (... + 7) % 7 ensures we end up with a value in the range [0, 6]
int daysUntilTuesday = ((int) DayOfWeek.Tuesday - (int) tomorrow.DayOfWeek + 7) % 7;
DateTime nextTuesday = tomorrow.AddDays(daysUntilTuesday);

EDIT: Just to make this nice and versatile:

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);
}

So to get the value for “today or in the next 6 days”:

DateTime nextTuesday = GetNextWeekday(DateTime.Today, DayOfWeek.Tuesday);

To get the value for “the next Tuesday excluding today”:

DateTime nextTuesday = GetNextWeekday(DateTime.Today.AddDays(1), DayOfWeek.Tuesday);