Question

我们有一个客户正在要求我们以这种方式对一些字符串进行排序（以与旧工具兼容）：

  A IR / 
  A IR +100bp 
  B IR / 
  B IR +100bp

如您所见，'/'和'+'颠倒了，标准顺序是相反的

  A IR +100bp 
  A IR / 
  B IR +100bp 
  B IR /

两个字符都是低ASCII表的一部分，因此非常稳定。

任何人都有一个主意是来自哪种语言或算法（我想这不是最后的惊喜）吗？

Answer 1

简单的答案是：因为它使用[String]::Compare() method并且返回相同的结果^{Thanks briantist}：

[String]::Compare('/','+')
# -1
# Less than zero: `strA` precedes `strB` in the sort order

更长的答案是：它不是ASCII / Unicode codepoint 常规值比较，而是{{3}中定义的 Unicode字符串比较 }。

后面的文档指向Unicode Collation Algorithm report中提供的Default Unicode Collation Element Table。下表为所有显式加权字符提供了从字符到排序规则元素的映射：

002B  ; [*063F.0020.0002] # PLUS SIGN
002F  ; [*03A1.0020.0002] # SOLIDUS

以下（恕我直言：有趣的）示例是使用（基于 .NET的）Powershell编写的，因为我不会说Java：

( '+-/*+−÷×' | 
    Get-CharInfo | 
        Format-Table -HideTableHeaders | 
            Out-String
).Split( [System.Environment]::NewLine,
         [System.StringSplitOptions]::RemoveEmptyEntries ) |
    ForEach-Object { $_.Trim() } |
        Sort-Object -Unique

结果：

- U+002D     DashPunctuation Hyphen-Minus
− U+2212          MathSymbol Minus Sign
* U+002A    OtherPunctuation Asterisk
/ U+002F    OtherPunctuation Solidus
+ U+002B          MathSymbol Plus Sign
× U+00D7          MathSymbol Multiplication Sign
÷ U+00F7          MathSymbol Division Sign

为完整起见，Get-CharInfo函数的定义如下：

<#
_get-CharInfo_1.1.ps1

Origin   by: http://poshcode.org/5234
             sorry, the above link is not available; last time checked 2018-05-07
Improved by: https://stackoverflow.com/users/3439404/josefz

Use this like this: "ábč",([char]'x'),0xBF | Get-CharInfo

Activate dot-sourced like this (apply a real path instead of .\):

. .\_get-CharInfo_1.1.ps1
#>

Add-Type -Name UName -Namespace Microsofts.CharMap -MemberDefinition $(
    switch ("$([System.Environment]::SystemDirectory -replace 
                '\\', '\\')\\getuname.dll") {
    {Test-Path -LiteralPath $_ -PathType Leaf} {@"
[DllImport("${_}", ExactSpelling=true, SetLastError=true)]
private static extern int GetUName(ushort wCharCode, 
    [MarshalAs(UnmanagedType.LPWStr)] System.Text.StringBuilder buf);

public static string Get(char ch) {
    var sb = new System.Text.StringBuilder(300);
    UName.GetUName(ch, sb);
    return sb.ToString();
}
"@
    }
    default {'public static string Get(char ch) { return "???"; }'}
    })

function Get-CharInfo {
    [CmdletBinding()]
    [OutputType([System.Management.Automation.PSCustomObject],[System.Array])]
    param(
        [Parameter(Position=0, Mandatory=$true, ValueFromPipeline=$true)]
        $InputObject
    )
    begin {
        Set-StrictMode -Version latest
        function out {
            param(
                [Parameter(Position=0, Mandatory=$true )] $ch,
                [Parameter(Position=1, Mandatory=$false)]$nil=''
                 )
            if (0 -le $ch -and 0xFFFF -ge $ch) {
                [pscustomobject]@{
                    Char = [char]$ch
                    CodePoint = 'U+{0:X4}' -f $ch
                    Category = [System.Globalization.CharUnicodeInfo]::GetUnicodeCategory($ch)
                    Description = [Microsofts.CharMap.UName]::Get($ch)
                }
            } elseif (0 -le $ch -and 0x10FFFF -ge $ch) {
                $s = [char]::ConvertFromUtf32($ch)
                [pscustomobject]@{
                    Char = $s
                    CodePoint = 'U+{0:X}' -f $ch
                    Category = [System.Globalization.CharUnicodeInfo]::GetUnicodeCategory($s, 0)
                    Description = '???' + $nil
                }
            } else {
                Write-Warning ('Character U+{0:X} is out of range' -f $ch)
            }
        }
    }
    process {
        if ($PSBoundParameters['Verbose']) {
            Write-Warning "InputObject type = $($InputObject.GetType().Name)"}
        if ($null -cne ($InputObject -as [char])) {
            #Write-Verbose "A $([char]$InputObject) InputObject character"
            out $([int][char]$InputObject) ''
        } elseif ($InputObject -isnot [string] -and $null -cne ($InputObject -as [int])) {
            #Write-Verbose "B $InputObject InputObject"
            out $([int]$InputObject) ''
        } else {
            $InputObject = [string]$InputObject
            #Write-Verbose "C $InputObject InputObject.Length $($InputObject.Length)"
            for ($i = 0; $i -lt $InputObject.Length; ++$i) {
                if (  [char]::IsHighSurrogate($InputObject[$i]) -and 
                      (1+$i) -lt $InputObject.Length -and 
                      [char]::IsLowSurrogate($InputObject[$i+1])) {
                    $aux = ' 0x{0:x4},0x{1:x4}' -f [int]$InputObject[$i], 
                                                   [int]$InputObject[$i+1]
                    Write-Verbose "surrogate pair $aux at position $i" 
                    out $([char]::ConvertToUtf32($InputObject[$i], $InputObject[1+$i])) $aux
                    $i++
                } else {
                    out $([int][char]$InputObject[$i]) ''
                }
            }
        }
    }
}

字符+和/的奇怪排序

1 个答案: