Get LastDayOfMonth,FirstDayOfMonth,LastDayOfPreviousMonth,FirstDayOfPreeviousMonth From Date

    public DateTime LastDayOfMonthFromDateTime(DateTime dateTime)

    {

        DateTime firstDayOfTheMonth = new DateTime(dateTime.Year, dateTime.Month, 1);

        return firstDayOfTheMonth.AddMonths(1).AddDays(-1);

    }

    public DateTime FirstDayOfMonthFromDateTime(DateTime dateTime)

    {

        return new DateTime(dateTime.Year, dateTime.Month, 1);

    }

    public DateTime LastDayOfPreviousMonthFromDateTime(DateTime dateTime)

    {

        DateTime firstDayOfTheMonth = new DateTime(dateTime.Year, dateTime.Month - 1, 1);

        return firstDayOfTheMonth.AddMonths(1).AddDays(-1);

    }

    public DateTime FirstDayOfPreeviousMonthFromDateTime(DateTime dateTime)

    {

        return new DateTime(dateTime.Year, dateTime.Month - 1, 1);

    }