递减运算符和递减赋值，不同的行为答案

【问题标题】：Decrement operator and decrement assignment, different behaviour递减运算符和递减赋值，不同的行为
【发布时间】：2020-05-10 14:42:26
【问题描述】：

您好，我们正在做这个编程练习：String doubles。

我们想通过详细的解释（如果可能的话，还有更多的例子一步一步）知道为什么这个代码：

using System;
using System.Text;

public static class Kata
{
  public static string Doubles(string str)
  {  
    Console.WriteLine("str: "+str);
    for(int i=0; i<str.Length-1;i++){
      if(str[i]==str[i+1]){
        str=str.Remove(i--,2); //➖➖ operator does not store the modified i value inside i?
        Console.WriteLine("str: "+str);
      }
    }
    return str;
  }
}

行为不同于：

using System;
using System.Text;

public static class Kata
{
  public static string Doubles(string str)
  {  
    Console.WriteLine("str: "+str);
    for(int i=0; i<str.Length-1;i++){
      if(str[i]==str[i+1]){
        str=str.Remove(i,2); 
        Console.WriteLine("str: "+str);
        i-=1; //➖= operator DOES store the modified i value inside i?
      }
    }
    return str;
  }
}

我们已阅读：

编辑：例如使用以下字符串：

zpezyhgwqevkekipkxboraceiehzpvajbjalaymsgvqlepelorhjgznaqtaghusuiypywzthoxasudhterdcwzvgyflmcgbjgfwqvefgmimdnzfsrgcpdqewohehvqlphqyzjvwpnbmpthydaiszcgnealtybeydagjvkndocgibgmxmnadtyxcynidjsxluzxelamjmpaxlfkjvsghmslztxuvevfymnawxwrtmnqinksdiopjwedqlnfqfqjblyfnlzanvybclifrmqfwczavthkdnvimztxucqjirndaediodolnylxkueowazqcdzilusmuimstcgvyrtolwnaxbmirxawfuwulawaeclrabiabhworlvpgrqnamqprwxmzegtrljvzwtlgkametzgnuzrlwawbwbdwgbkelrutpfgoerdmtrmjhlryouvrxkjixpyrpcpqkmfhvnajhfptpvklwcwewyrptmxrpjurafthzirncdtdachdgmtgqhqgtompqfzyuerjrolicsenpqetgedhxupmqsocbmnoebhdlcusbldyrcksjmcrofsyzjgpeqjniahdjlgmqrkoblsjdblmbhogkveotmtetjkfcqlokxudwnqxmcewmbmatosohbxyvxrjyxzuamxrmgyfbhcrhwxjloyxhizwizvhyocjvzeuonpnmazfqyezmpwdfprpyzjtinoxasnculkgitgjvwvjdrnsupdzpqesrlrsymljulsygxioemyzkxkiyvjihroxcnlikloqebavjgqamrusbtiqlzdajiuvdvcmkihcoseiwpxifwapmaxzmalvxqohazilysuvhodnphzfmuhskhqohikfbohgmjyhvrsjwzozgprjwnaioavklbnoyxejvqheypzblrzhcuoaozrmonvjgqwhaqvwuacrokinpekdiqnvwyieribtjpedqjmgznpalerexkdrbpdbkchrfl zzayilnbrcqzfwmelrnufdtobvanohrmeswmxbadvoqdesajsrlgtesvcdlyetpztoqpvbifxyrhnepxzstxcfwvsxjqdlcapdawkrwmeupgiezcuxfvmlszjkvhufenpladmhwhwabcgloeqbrfqpelilrugypcrxevpmbyzljqtxwtozskzbzkpcucmeurauledwueforkpzcmjpjwbtwqixrhdpdeqwhjvwaqfljovqzhswuxpgrmnwnykchkjgeaunvloldyvsyjogvfojyjrijdcgahgkgsdscgbesnusruyekehbwzivilerihkwslmvdodkrlpzrofyafogkhkrckwkcxafisxoasxliwfjtpmjlownxfvylmltngirymgnbhvcynxnymzobnhdwzdohexclhjyiespfvhiwkoyvbhuqkecrbdgzcewznpqdzeuvlhmwoctzwxacghgampdrkuyuwxmyecsgdzkgquhbfqpnwsxujwevlftzbnmzhvsxkzdhqfyidsekydzrpiyxvxfkfdhitjxrdwopedxwlcuqpizpgkznegcfavabpuvmhbojnclsweponyiecmspsinzdcvknhfijoupcvzxbljypmibskriurigwogafoyheyetbhnvogypkrutscqwosfotombgvzjxzvzdchgdqonicxbtmtqznuxemzdpcjkvhbcgmkvbdsdnupgzvoxuqderbhdrpjqaexqjncyvbuwfruptxseuyzcvjoxldugxixzwlspbtwhyzmsicvlywkzqhstkypqbyugrvsiedcacsdvojibyxiptzfgfaeganjngutkdnjghtpthtmdofxywvndvbzvbnhoaklwcruxylklygafybxvnbkafgshgmsclbsrdgezxctfspauwaqmazalrvzmrlsiaenzngxodhgaodhmqslztuahaihsimjlencbgqcavmvseqhwefvawalsygfpj xgqyabgfapldgyhckalodrioecjcaknrygfujuhvyzuxeuqdvoxjcypgrxrdepctfztnsptqpdwxdgxpmwoytodgejdfirseaclfvhtzcsdkzcribdaqwnjpmjmuirolotojliclulasjbdnderbintwtmuzrkdswgnhwsbovsjxotzlqvnjtmkbpopqrvmtwdnwqlgqdwhzmtyjwmrickxafqpgxwyufcgqguxthpeimpwojnhbeijtknhbcqkorunidcoxamfpnpuawkpxqwsmkajkmgnoxbabjfmghwnqsutgesbnxuydsdluzortzvajkjpwythprgbunkaedgmjvmwvzedzgjsrdoefcevcmesfehtzrtxbocadtcmrzscvhmzuxylkwqtqrsqpfhrzubaceyksqufadiozctinexikmblwlsbcbfmxpynstbktnispbfeyqgxctumjgtjnzaguoqkdfqtcmpwdjvufncmvijdvlelzsxumbxbkvbsanuqexialydawolmfnorbetjoukclumjlhntzxdepxplwxgjrwtkbjngoqotnmdeymnroxesurwlmaymrpndrqkwpjmwjlvlmprbqjmbtnrcpkunqvuxhshugyilqbnocnimnhdidbrjgyqhurpmicnwurlrzd P>

我们看到了：

【问题讨论】：

str 的值是多少，它们的行为有什么不同？
您使用哪些 .NET 实现（.NET Framework、.NET Core、...）？在 Framework 4 - 4.8 中运行平稳，两个函数在给定输入下的输出是相同的。
向您展示我使用的代码：dotnetfiddle.net/Usxucs 也许您看到了不同。

标签： c# operators

【解决方案1】：

在第一种情况下，i的值发生了变化，但是我们将当前值传递给Remove方法后，如果我们想将新值传递给Remove方法，我们将减量运算符放在前面： --i 或在单独的行上做：

 i--;
 str = str.Remove(i,2);

【讨论】：