如何在字符串中查找特定数量的数字

Question

我不明白正则表达式:( 我想查找路径是否仅包含 7 位数字 例如：

C:\Users\3D Objects\1403036 --> the result should be 1403036

C:\Users\358712\1403036 --> the result should be 1403036

等等

我努力了：

$FilesPath -match '([\d{1,7}]{7})')

和

$FilesPath -match '(\d{7})')

目前我正在处理：

$FilesPath = Read-Host -Prompt
if ($Matches[1].Length -eq '7') {
        $FolderNumber = $Matches[1] 
    }

这是不对的，因为如果路径中包含数字 3 则不匹配

如果是这种情况：

C:\Users\3D Objects\1403036854 --> More than 7 digits the result should be empty

或者

C:\Users\3874113353D Objects\1403036 --> Should return result for 1403036

我没有数组，只是想知道是否有一个数字正好是 7 位数字，如果包含少于或多于 7 位数字则没有

Answer 1

你的意思是这样的？

# as example the paths as aray to loop over
'C:UsersD Objects`3036', 'C:Users8712`3036', 
'C:UserssomewhereS4567', 'C:UsersD Objects`3036854' | ForEach-Object {
    # return the number anchored at the end of the string with exactly 7 digits
    ([regex]'D(d{7})$').Match($_).Groups[1].Value
}

输出：

1403036
1403036
1234567

---

这个：

$path = 'C:UsersD Objects`3036'
$result = ([regex]'D(d{7})(?:D|$)').Match($path).Groups[1].Value

直接将匹配分配给变量$result，如果匹配或$null将是匹配的数值。正则表达式方法.Match() 不填充 $matches 数组。

使用正则表达式操作员，它确实填充了 $matches 数组，您也可以这样做：

if ($path -match 'D(d{7})(?:D|$)') {
    $result = $matches[1]
}

正则表达式详细信息：

D           # Match a single character that is NOT a “digit” (any decimal number in any Unicode script)
(            # Match the regex below and capture its match into backreference number 1
   d        # Match a single character that is a “digit” (any decimal number in any Unicode script)
      {7}    # Exactly 7 times
)
(?:          # Match the regular expression below
             # Match this alternative (attempting the next alternative only if this one fails)
      D     # Match a single character that is NOT a “digit” (any decimal number in any Unicode script)
   |
             # Or match this alternative (the entire group fails if this one fails to match)
      $      # Assert position at the end of the string, or before the line break at the end of the string, if any (line feed)
)