C#获取上个月第一天和最后一天

private DateTime FirstDayOfPreviousMonth(DateTime datetime)
...{
    return datetime.AddDays(1 - datetime.Day).AddMonths(-1);
}

		

private DateTime LastDayOfPrdviousMonth(DateTime datetime)
...{
    return datetime.AddDays(1 - datetime.Day).AddDays(-1);
}

		

private DateTime FirstDayOfMonth(DateTime datetime)
...{
    return datetime.AddDays(1 - datetime.Day);
} 

		

private DateTime LastDayOfMonth(DateTime datetime)
...{
    return datetime.AddDays(1 - datetime.Day).AddMonths(1).AddDays(-1);
}