Powershell：从字符串中提取 mediaid

Question

我想从字符串

中提取mediaid

"\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e",

如何做到？

Answer 1

您可以使用Substring功能。语法为：.Substring( StartIndex [, length] )

$string= '\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e'
$mediaid = $string.Substring($string.Length - 148, 36)

Answer 2

一种选择是使用正则表达式：

$text = '"\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e"'

[Regex]::Match($text, '(?<={).*(?=})').Value

哪个returns:

2EB3AFF5-24C6-4C1F-8957-37CBFCBED751

Answer 3

由于发布的问题中缺少要求，可能需要某种正则表达式：

要在这种情况下提取 mediaid 或引用的 GUID 之前的任何标识符名称，您可以执行以下操作：

$str = '"\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e",'
$regex = [regex]'\S+(?==\"{[-A-F0-9]+}\")'
$regex.Match($str).Value

要提取 mediaid 的值，您可以执行以下操作：

$str = '"\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e",'
$regex = [regex]'(?<=mediaid=)\S+'
$regex.Match($str).Value

解释：

\S+：匹配非空白字符一次或多次(+)
(?=<something>)：<something> 的正面前瞻，但未捕获字符
(?<=): Positive lookbehind for ` 但不捕获
[A-F0-9-]：字符 class 匹配，包括大写 A 到 F、零到九和 -（破折号）。请注意，这里强制使用大写字母，因为我们使用的是 .NET class Regex。通常，Windows PowerShell 不区分大小写，而无需另行指定，例如$str -match '[A-F]' 将匹配 a-f 或 A-F.

Answer 4

您也可以使用正则表达式 -replace 运算符来执行此操作，您只需捕获要保留的内容并删除所有其余内容：

$string= '\u003cimage mediaid=\"{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}\" alt=\"Caulfield to Dandenong Level Crossing Removal\" height=\"\" width=\"\" hspace=\"\" vspace=\"\" /\u003e'
$string -replace '.*mediaid=\?"({[0-9A-F-]+}).*', ''

结果：

{2EB3AFF5-24C6-4C1F-8957-37CBFCBED751}

正则表达式详细信息：

.                    Match any single character that is not a line break character
   *                 Between zero and unlimited times, as many times as possible, giving back as needed (greedy)
mediaid=             Match the characters “mediaid=” literally
\                   Match the character “\” literally
   ?                 Between zero and one times, as many times as possible, giving back as needed (greedy)
"                    Match the character “"” literally
(                    Match the regular expression below and capture its match into backreference number 1
   {                 Match the character “{” literally
   [0-9A-F-]         Match a single character present in the list below
                     A character in the range between “0” and “9”
                     A character in the range between “A” and “F”
                     The character “-”
      +              Between one and unlimited times, as many times as possible, giving back as needed (greedy)
   }                 Match the character “}” literally
)
.                    Match any single character that is not a line break character
   *                 Between zero and unlimited times, as many times as possible, giving back as needed (greedy)

Powershell：从字符串中提取 mediaid

Powershell: extract mediaid from string

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