提取字符串中文件扩展名 (.ps1) 之前的数字

创建文件的 cmdlet 返回一个文本块，其中包含文件的名称。该文件的格式为字符串[数字].ps1，但数字是随机的，所以我想提取该数字并将其存储在变量中。

供参考的文本块：

  +         ~~~~~\nA 'using' statement must appear before any other statements in\
    \ a script.\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script35.ps1:20 char:8\n+         using Microsoft.Build.Framework;\n\
    +              ~\nMissing using directive\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script35.ps1:20 char:3\n+         using Microsoft.Build.Framework;\n\
    +         ~~~~~\nA 'using' statement must appear before any other statements in\
    \ a script.\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script35.ps1:21 char:8\n+         using Microsoft.Build.Utilities;\n\
    +              ~\nMissing using directive\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script35.ps1:21 char:3\n+         using Microsoft.Build.Utilities;\n\
    +         ~~~~~\nA 'using' statement must appear before any other statements in\

我想$result -match '\d\d+(?=\.\w+)'可以，但它只返回找到该号码的行，而不仅仅是号码。

With a 收藏（而不是单个值）作为 LHS，-match操作员:

• 充当filter- 即返回子数组匹配元素而不是布尔值

• does not填充自动的$Matches多变的与匹配运算符的结果。

这就是为什么你的输出包含匹配行作为一个整体.

要仅返回匹配的部分，您可以使用switch陈述与-Regex循环遍历行数组的选项，在这种情况下$Matches is为每个输入行填充：

# Array of sample lines.
# For illustrative purposes I've tweaked the `script<number>.ps1`
# tokens to have successive numbers.
$lines = @'
 +         ~~~~~\nA 'using' statement must appear before any other statements in\
    \ a script.\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script35.ps1:20 char:8\n+         using Microsoft.Build.Framework;\n\
    +              ~\nMissing using directive\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script36.ps1:20 char:3\n+         using Microsoft.Build.Framework;\n\
    +         ~~~~~\nA 'using' statement must appear before any other statements in\
    \ a script.\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script37.ps1:21 char:8\n+         using Microsoft.Build.Utilities;\n\
    +              ~\nMissing using directive\nAt C:\\Packages\\Plugins\\Microsoft.CPlat.Core.RunCommandWindows\\\
    1.1.3\\Downloads\\script38.ps1:21 char:3\n+         using Microsoft.Build.Utilities;\n\
    +         ~~~~~\nA 'using' statement must appear before any other statements in\
'@ -split '\r?\n'

# Perform the matching, line by line,
# and output each line's matching part,
# resulting in an array of strings.
# Prepend 
#     $result = 
# to store the array in a variable.
switch -Regex ($lines) {
  '\d+(?=\.\w+)' { $Matches[0] } # to extract only the *1st* match,
                                   # append `; break` inside the { ... }
}

上面的结果是：

35
36
37
38

注意switch还支持直接从文件中读取行，使用-File option
(switch -Regex -File $filePath { ... }).