Powershell：如何获取文本的子字符串

Question

我有一个字段，description，其中包含可预测格式的文本，看起来像这 2 个选项中的任何一个，

DEACTIVATED on Tue Apr 02 2019

或

DEACTIVATED on Tue Apr 02 2019 | MANAGER John Smith

我需要在每种情况下只获取日期，Tue Apr 02 2019，同时考虑日期之后是否有文本。

示例用例

$string = "DEACTIVATED on Tue Apr 02 2019 | MANAGER John Smith"
$date   = "Tue Apr 02 2019"

Answer 1

不确定我是否理解正确，但子字符串是这样工作的：

$string = "DEACTIVATED on Tue Apr 02 2019 | MANAGER John Smith"
#.substring(starting point, how many)
$date = $string.Substring(15,10)
$date
Tue Apr 02

Answer 2

这是我得到它的方式，因为我必须考虑对象之间的一些潜在差异

$text = "DEACTIVATED on Tue Apr 02 2019 | MANAGER John Smith"
$start_pos = $text.IndexOf('on')

$substring = $text.substring($start_pos + 3)

if ($text.IndexOf(' | ') -gt -1) {
    $end_pos = $text.indexOf(' | ')
    $substring = $substring.substring(0, $end_pos)
}

Answer 3

这里有一个稍微不同的方法来完成这项工作。 [咧嘴一笑]

它的作用...

前 4 行创建了一个字符串数组以用于
遍历集合
在“|”上拆分
取结果数组中的第一项
删除所有 leading/trailing 空格
使用命名捕获组获取 DEACTIVATED on
显示生成的命名捕获组
将其转换为 [datetime] 对象并显示

这是代码...

$DescriptionText = @(
    'DEACTIVATED on Sat May 11 2019'
    'DEACTIVATED on Tue Apr 02 2019 | MANAGER John Smith'
    )

foreach ($DT_Item in $DescriptionText)
    {
    $Null = $DT_Item.Split('|')[0].Trim() -match 'DEACTIVATED on (?<DeactivationDate>.+)'

    $Matches.DeactivationDate
    [datetime]::ParseExact($Matches.DeactivationDate, 'ddd MMM dd yyyy', $Null)
    '=' * 20
    }

输出...

Sat May 11 2019

2019 May 11, Saturday 12:00:00 AM
====================
Tue Apr 02 2019
2019 April 02, Tuesday 12:00:00 AM
====================

我想不通第一对输出中的空白行是从哪里来的。 [脸红]

Answer 4

我会使用：

带有 positive lookbehind zero length assertion
cast/convert 到 [datetime] 输入 ::ParseExact()

## Q:\Test19\SO_56060672.ps1

$strings = @"
DEACTIVATED on Tue Apr 02 2019

DEACTIVATED on Tue Apr 09 2019 | MANAGER John Smith
"@ -split '\r?\n'

$RE = '(?<=DEACTIVATED on ).*\d{4}'

## Output found datetime strings
$strings | Select-String $RE | ForEach-Object{$_.Matches.value}

## if your locale is English convert to [datetime] type
$strings | Select-String $RE | ForEach-Object{
    [datetime]::ParseExact($_.Matches.value,'ddd MMM dd yyyy',$null)
}

## if your locale is NOT English convert to [datetime] type
$strings | Select-String $RE | ForEach-Object{
    [datetime]::ParseExact($_.Matches.value,'ddd MMM dd yyyy',
       [System.Globalization.CultureInfo]::InvariantCulture)
}

我的德语语言环境中第一个和最后一个的输出：

Tue Apr 02 2019
Tue Apr 09 2019

Dienstag, 2. April 2019 00:00:00
Dienstag, 9. April 2019 00:00:00

Powershell：如何获取文本的子字符串

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