Powershell 排序命令未按预期工作

Question

我使用这组命令来检查键盘字符上的排序命令。

$symb="a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","²","1","2","3","4","5","6","7","8","9","0","°","+","&","é",'"',"'","(","-","è",[regex]::escape('`'),"_","ç","à",")","=","~","#","{","[","|","\","^","@","]","}","$","¨","ˆ","£","¤","ù","*","%","µ","<",",",";",":","!",">","?",".","/","§","€"; $symb|sort|ac file.txt;(gc file.txt)-join""

这是我在文件和控制台中得到的内容。

'-!"#$%&()*,./:;?@[\]ˆ^_`{|}~¨£¤€+<=>§°µ012²3456789aAàbBcCçDdEeéèfFgGhHIiJjKkLlmMNnOoPpqQRrsStTuUùvVwWXxyYzZ

在大约一半的小写和大写字母对的情况下，顺序是相反的；似乎它应该总是“小写在前，大写在后”。如何解决这个问题？

Answer 1

PowerShell - 与 .NET 框架的类型不同 - 默认情况下不区分大小写；如果您想要区分大小写的行为，则需要选择加入。

以Sort-Object为例您需要使用其 -CaseSensitive 开关:

PS> -join ('a', 'B', 'A', 'b' | Sort-Object -CaseSensitive)
aAbB

正如您所料，这会导致小写字母首先排序，因为在(美国英语)排序顺序中，小写字母的排序权重低于大写字母 - 即使尽管就其 Unicode 代码点而言，关系是相反的(例如，[int] [char] 'a' 是 97，而 [int] [char]'A'是65)。

(如果数组包含 [char] 实例，则将应用基于代码点的排序，但 PowerShell 没有 [char] 文字，因此文字如 'a' 是长度为 1 的 [string]；但是，您可以使用显式强制转换: -join ([char] 'A', [char] 'a' | Sort-Object -CaseSensitive) 产生 'Aa'，即排序大写 首先。)

---

如果没有 -CaseSensitive，给定字母的小写和大写变体具有相同的排序权重，因此不能保证它们之间的特定顺序。

例如，以下循环会快速退出:

$prevResult = $null
while ($true) { 

  # Get a shuffled array of lower- and uppercase letters.
  $arr = 'a', 'B', 'A', 'b'
  $arr = $arr | Get-Random -Count $arr.Count

  # Sort it case-INsensitively.
  $result = -join ($arr | Sort-Object)

  $result # output

  # See if the result is different from the previous one.
  # Note the use of -cne rather than just -ne:
  # -ce is the case-*sensitive* variant of -ne
  if ($prevResult -and $prevResult -cne $result) {
    Write-Warning "Output order has changed."
    break
  }
  $prevResult = $result

} 

但是，请注意，Sort-Object 似乎执行稳定排序:也就是说，对于给定的输入数组，结果数组始终相同。 也就是说，如果将 $arr 的创建移到 while 循环之外，结果始终相同，并且循环永远不会退出。