从Datetime.Today减去一个月 [英] Subtract one month from Datetime.Today

问题描述

我有一个 DateTimePicker ，允许用户选择当前年份之前的月份.

I have a DateTimePicker in which I allow user to select month previous to the current year.

问题是，如果日期是1月1日，那么它就无法像我现在那样计算去年的12月.

The problem is, that if the date is 1st January, it can't calculate the December month of last year in the way I am doing it now.

var today = DateTime.Today;

var lastmonth = new DateTime(today.Year, today.Month - 1, 1);
if (qs == "")
{
    dateTimePicker1.MaxDate = lastmonth;
    dateTimePicker1.Value = lastmonth;
}
else
{
    DateTime dt = Convert.ToDateTime(qs);

    dateTimePicker1.Value = dt;
    dateTimePicker1.MaxDate = lastmonth;
}

推荐答案

只需通过添加" -1减去一个月:

Just substract a month by 'adding` -1:

var lastmonth = DateTime.Today.AddMonths(-1);

请参阅 DateTime上的MSDN文档..AddMonths .

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