将单词的每个最后一个字母与 C# 中的下一个单词相连

Question

There is an interview question that asks me to attach every last letter of the word with the next word in C#. For example the input is "Hey hello world" and the output should be "He yhell oworld".

I've come up with the code below but is there a better way to do this? Perhaps in LINQ?

string inputString = "Hey Hello World";
string[] stringArray = inputString.Split(' ').ToArray();
StringBuilder resultString = new StringBuilder("");
StringBuilder lastLetter = new StringBuilder(""); 

for (int i = 0; i < stringArray.Length; i++)
{
    string temp = stringArray[i].ToString();

    if (i < stringArray.Length - 2)
    {
        resultString.Append(lastLetter + temp.Substring(0, temp.Length - 1));
        lastLetter.Clear();
        lastLetter.Append(" " + temp.Substring(temp.Length - 1, 1));
    }
    else
        resultString.Append(lastLetter + temp.Substring(0, temp.Length));
}

Console.WriteLine(resultString);

Answer 1

如何使用正则表达式

var newtext = Regex.Replace("Hey hello world", @"(.) "," $1");

Answer 2

You are unnecessarily complicating the code. Simply replace space with previous character.

        var input = "Hey Hello world";
        var arr = input.Trim().ToCharArray();
        for(int i =0; i< arr.Length; i++)
        {
            if(arr[i]==' ')
            {
                var temp = arr[i];
                arr[i] = arr[i - 1];
                arr[i - 1] = temp;
            }
        }
        Console.WriteLine(arr);

Answer 3

Here's a LINQ solution, since that seems to be what the OP is looking for.

using System;
using System.Linq;

public class Program
{
    const char space = ' ';

    public static string DoHomework(string input)
    {
        return new string
        (
            input.Select( (c,i) => 
            {
                if (i == 0 || i == input.Length-1) return c;
                if (c == space) return input[i-1];
                if (input[i+1] == space) return space;
                return c;
            }).ToArray()    
        );
    }

    public static void Main()
    {
        var input = "Hey hello world";
        var output = DoHomework(input);

        Console.WriteLine(output);
    }
}

Output:

He yhell oworld

Try it out on DotNetFiddle