VBA不能减去日期。

I’m trying to get the date 4 days older than now. Here is my code

我想把日期提前4天。这是我的代码

Sub calcdate()
Dim nDateTime, oDateTime As Date
nDateTime = Format(Now, "YYMMDD")
oDateTime = Format(DateAdd("d", -4, nDateTime), "YYMMDD")
MsgBox ("Today is " & nDateTime & " And OldDate is " & oDateTime)
End Sub

But output is ‘Today is 170604 And OldDate is 02-10-3734”

但是输出是"今天是170604,OldDate是02-10-3734 "

I Tried to do it without DateAdd

我试着不使用DateAdd

nDateTime = Format(Now, "YYMMDD")
oDateTime = nDateTime - 4

*Output is ‘Today is 170604 And OldDate is 170604’

*输出为“今天为170604,OldDate为170604”

I tried these changes

我试着这些变化

nDateTime = Format(Now, "YYMMDD")
oDateTime = DateAdd("d", -4, nDateTime)

*Output is ‘Today is 170604 And OldDate is 31-01-2367’

*输出是“今天是170604,OldDate是31-01-2367”

nDateTime = Format(Now, "YY-MM-DD")
oDateTime = Format(DateAdd("d", -4, nDateTime), "YY-MM-DD")

*Output is ‘Today is 17-06-04 And OldDate is 04-06-2013’

*输出为“今天17-06-04,OldDate 04-06-2013”

So it seems here it is subtracting years although I put “d”.

所以它看起来是减去年份虽然我写的是d。

last thing i tried:

最后我尝试:

nDateTime = Format(Now, "DD-MM-YY")
oDateTime = Format(DateAdd("d", -4, nDateTime), "DD-MM-YY")

*Output is ‘Today is 04-06-17 And OldDate is 31-05-2017’ i want this date, in format 170531, also why did it give me 2017 while i choose format YY only?

*输出是“今天是04-06-17,OldDate是31-05-2017”我想要这个日期，格式是170531，为什么给我2017，而我只选择格式YY ?

2 个解决方案

#1

Format creates a string so you can no longer sensibly perform calculations on it. Do your formatting afterwards instead:

格式创建一个字符串，这样您就不能对其进行合理的计算。然后进行格式化:

Dim nDateTime As Date, oDateTime As Date
nDateTime = Now
oDateTime = nDateTime - 4
MsgBox "Today is " & Format(nDateTime, "YYMMDD") & " And OldDate is " & Format(oDateTime, "YYMMDD")

Also, you need to declare the variable type for each variable so, as I've done.

同样，您需要为每个变量声明变量类型，正如我所做的。

#2

because Format(Now, "YYMMDD") result is string

因为格式(现在是“YYMMDD”)的结果是字符串

Dim myDate As Date
Dim nDatetime As String, oDateTime As String

myDate = Now
nDatetime = Format(myDate, "yymmdd")
oDateTime = Format(DateAdd("d", -4, myDate), "YY-MM-DD")

#1