public static class DateRange 

private void SetValue()
{
    // Use name to access the cell.
    this.gcCalendarGrid1.Template.Content[2, 0].Name = "cell1";

    // Set value to a cell in today.
    this.gcCalendarGrid1[DateTime.Today][1, 0].Value = "abc";
    this.gcCalendarGrid1[DateTime.Today]["cell1"].Value = "abc";

    // Set value to the cells in a date range.
    IEnumerable<DateTime> dateRange = DateRange.CreateDateRange(new DateTime(2014, 2, 1), new DateTime(2014, 2, 20));
    this.gcCalendarGrid1[dateRange][1, 0].Value = "abc";
    this.gcCalendarGrid1[dateRange]["cell1"].Value = "abc";

    // Set value to the cells in a yearly recurrence.
    IEnumerable<DateTime> yearlyDate = DateRange.CreateYearlyDayRecurrence(new DateTime(2000, 2, 1), 1, 100);
    this.gcCalendarGrid1[yearlyDate][1, 0].Value = "abc";
    this.gcCalendarGrid1[yearlyDate]["cell1"].Value = "abc";

    // Set value to the cells in a monthly weekday recurrence.
    IEnumerable<DateTime> monthlyWeekday = DateRange.CreateMonthlyWeekDayRecurrence(new DateTime(2014, 1, 1), DayOfWeekInMonth.Last, DayOfWeek.Friday, 1, new DateTime(2014, 12, 31));
    this.gcCalendarGrid1[monthlyWeekday][1, 0].Value = "abc";
    this.gcCalendarGrid1[monthlyWeekday]["cell1"].Value = "abc";

    // Set value to many cells. By the SetValue method, we can get better performance.
    for (int row = 0; row < this.gcCalendarGrid1.Template.RowCount; row++)
    {
        for (int column = 0; column < this.gcCalendarGrid1.Template.ColumnCount; column++)
        {
            this.gcCalendarGrid1.SetValue(DateTime.Today, row, column, "abc");
        }
    }

    // Clear the values and formats set to a date, to release the memory.
    this.gcCalendarGrid1.Clear(DateTime.Today);

    // Clear all the values and formats, to release the memory.
    this.gcCalendarGrid1.ClearAll();
}