减去VBA中的日期?

I'm having big problems doing operation with the date in Excel VBA. I have a form that has a textbox where the user will enter the date. The problem is that he may enter it in different formats (eg, 1.08.2011 for 1st of August, or 8/1/11 for the same day). Now what I want to do is to subtract some days from that date that he enters in the TextBox. I had to success so far and I don't know how to do it. I tried something like this

我在用Excel VBA做操作时遇到了大问题。我有一个表单，它有一个文本框，用户可以在其中输入日期。问题是他可能会以不同的格式输入(例如，8月1日的1.08.2011，或者同一天的8/1/11)。现在我要做的是减去他在文本框中输入的日期。到目前为止，我已经取得了成功，但我不知道如何去做。我试过了

Format((Format(Me.datalivrare.Value, "dd.mm.yyy") - 4), "dd.mm.yyyy")

Where datalivrare is that textbox where the user enters the date and 4 is the number of days I want to subtract from that date... and I want the format to always be dd.mm.yyyy no matter what they enter in that textbox.

datalivrare是用户输入日期的文本框，4是我想从日期中减去的天数。我希望格式总是。mm。yyyy，不管他们在那个文本框里输入什么。

4 个解决方案

#1

I suggest looking at the DateAdd function for VBA

我建议查看VBA的DateAdd函数

http://www.techonthenet.com/excel/formulas/dateadd.php

http://office.microsoft.com/en-us/access-help/dateadd-function-HA001228810.aspx

You could do the following:

你可以这样做:

Format(DateAdd("d", -4, CDate(Me.datalivrare.Value)), "dd.mm.yyyy")

#2

the best to add and substract from dates on vba is dateadd() (with negative number for substractions) also, in your example code there's a missing y on the format string (it accepts 1, 2 or 4 y, only)

在vba上添加和减除日期的最佳方法是dateadd()(下标为负数)，而且，在示例代码中，格式字符串中缺少y(它只接受1、2或4 y)

#3

First cast to Date, then subtract days, then format appropriately:

首先是到日期，然后减去天数，然后适当格式化:

Format(DateAdd("d", -4, CDate(Me.datalivrare.Value)), "dd.mm.yyyy")

#4

It is important to check if the user entered a value that VBA can interprit as a date so first you should:

重要的是要检查用户是否输入了VBA可以作为日期插入的值，所以首先您应该:

If isDate(Me.datalivrare.Value) Then
    str_Date = Format(DateAdd("d", -4, CDate(Me.datalivrare.Value)), "dd.mm.yyyy")
Else
    MsgBox "Not a valid date value", vbCritical + vbOkOnly, "Invalid Entry"
End If

I think bluefeet's answer had the most information so far and I borrowed the use of DateAdd and CDate.

我认为bluefeet的回答提供了最多的信息，我借用了DateAdd和CDate的用法。

#1