whats the simplest way to calculate the Monday in the first week of the year

Question

i want to pass in a year and get a date back that represents the first monday of the first week

so:

• If a passed in 2011, i would get back Jan 3, 2011
• If a passed in 2010, i would get back Jan 4, 2010

Answer 1

private DateTime GetFirstMondayOfYear(int year)
{
    DateTime dt = new DateTime(year, 1, 1);

    while (dt.DayOfWeek != DayOfWeek.Monday)
    {
        dt = dt.AddDays(1);
    }

    return dt;
}

Answer 2

Try this for a solution without looping:

public DateTime FirstMonday(int year)
{
    DateTime firstDay = new DateTime(year, 1, 1);

    return new DateTime(year, 1, (8 - (int)firstDay.DayOfWeek) % 7 + 1);
}