Subtract/Add 天到使用 Write-Host 的预定义日期

Question

我正在尝试显示里程碑。我在下面尝试过，但出现错误，显示 Method invocation failed because [System.String] does not contain a method named 'AddDays'. 我在前一行中预定义了 $lastmodified，它是 12/28/2015 0:00

$predetermined=[system.datetime]$LastModified
$date= ($predetermined).AddDays(30).ToString("MM/dd/yyyy:")

$date5 = ($date).AddDays(-15).ToString("MM/dd/yyyy:")
$date4 = ($date).AddDays(-12).ToString("MM/dd/yyyy:")
$date3 = ($date).AddDays(-9).ToString("MM/dd/yyyy:")
$date2 = ($date).AddDays(-6).ToString("MM/dd/yyyy:")
$date1 = ($date).AddDays(-3).ToString("MM/dd/yyyy:")

write-host -foregroundcolor Green "$date5 Action 1"
write-host -foregroundcolor Green "$date4 Action 2"
write-host -foregroundcolor Green "$date3 Action 3"
write-host -foregroundcolor Green "$date2 Action 4"
write-host -foregroundcolor Green "$date1 Action 5"
write-host -foregroundcolor Green "$date Action 6"

我的输出应该是

12/23/2015: Action 1"
12/26/2015: Action 2"
12/19/2015: Action 3"
12/22/2015: Action 4"
12/25/2015: Action 5"
12/28/2015: Action 6"

Answer 1

在你的代码中做这样的事情：

function Get-DateFmt1
{
    param (
        [Parameter(Mandatory=$true, Position=0)]
        [DateTime] $Date
    )

    $Date.ToString("MM/dd/yyyy")
}

$LastModified = [DateTime]::Parse('12/28/2015')
# ....
$predetermined=[DateTime]$LastModified
$date = ($predetermined).AddDays(30)

$date5 = $date.AddDays(-15)
$date4 = $date.AddDays(-12)
$date3 = $date.AddDays(-9)
$date2 = $date.AddDays(-6)
$date1 = $date.AddDays(-3)

Write-Host -Foregroundcolor Green "$($date5.ToString("MM/dd/yyyy")): Action 1"
Write-Host -Foregroundcolor Green "$($date4.ToString("MM/dd/yyyy")): Action 2"
Write-Host -Foregroundcolor Green "$($date3.ToString("MM/dd/yyyy")): Action 3"
# or write a helper function if that makes sense to you
Write-Host -Foregroundcolor Green "$(Get-DateFmt1 $date2): Action 4"
Write-Host -Foregroundcolor Green "$(Get-DateFmt1 $date1): Action 5"
Write-Host -Foregroundcolor Green "$(Get-DateFmt1 $date): Action 6"

Answer 2

错误就在眼前：方法调用失败，因为[System.String]不包含名为'AddDays'[=26=的方法]

您正在尝试使用 AddDays()，这是 DateTime-class 中的一个方法，但 $date 不是 DateTime 对象，因为你把它变成了一个字符串

$date= ($predetermined).AddDays(30).ToString("MM/dd/yyyy:")

如果您要使用它来创建其他变量，则需要将 $date 保留为 DateTime 对象。例如：

$predetermined=[system.datetime](get-date)
$date = $predetermined.AddDays(30)

$date5 = $date.AddDays(-15).ToString("MM/dd/yyyy:")
$date4 = $date.AddDays(-12).ToString("MM/dd/yyyy:")
$date3 = $date.AddDays(-9).ToString("MM/dd/yyyy:")
$date2 = $date.AddDays(-6).ToString("MM/dd/yyyy:")
$date1 = $date.AddDays(-3).ToString("MM/dd/yyyy:")
#Convert `$date` to string using specified format
$date0 = $date.ToString("MM/dd/yyyy:")

write-host -foregroundcolor Green "$date5 Action 1"
write-host -foregroundcolor Green "$date4 Action 2"
write-host -foregroundcolor Green "$date3 Action 3"
write-host -foregroundcolor Green "$date2 Action 4"
write-host -foregroundcolor Green "$date1 Action 5"
write-host -foregroundcolor Green "$date0 Action 6"

更新：故障排除步骤.. 您收到的错误不仅仅是消息。它还说是哪一行导致了错误。

Method invocation failed because [System.String] does not contain a method named 'AddDays'.
At line:4 char:1
+ $date5 = ($date).AddDays(-15).ToString("MM/dd/yyyy:")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : MethodNotFound

上面还说AddDays()不是System.String中的方法，那我们看看你反对你在AddDays()上调用了什么：

($date).AddDays(-15)...

这意味着 $date 是一个字符串对象。为什么会这样？那是因为它包含 ToString() 方法的结果。

$date= ($predetermined).AddDays(30).ToString("MM/dd/yyyy:")

Subtract/Add 天到使用 Write-Host 的预定义日期

Subtract/Add days to a predefined date using Write-Host

variables

powershell

date

tostring

write-host