我試圖在不使用內置函式的情況下將一個字串插入另一個字串

class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Your string: ");
            string str = Console.ReadLine();

            
            stringFuncs.Insert(str, "Hello", 5);

            
        }
    }

public static string SubString(string word,int a, int b)
        {

            for(int i = a; i < b; i  )
            {
                Console.Write(word[i]);//my substring method
            }
            return word;
        }
public static string Insert(string word, string subs, int index)
        {
            
            int numberOfLetters = 0;
            foreach (var c in word)
            {
                numberOfLetters  ;
            }

            
            Console.WriteLine(stringFuncs.SubString(word, 0, index)   subs   stringFuncs.SubString(word, index,numberOfLetters-index));
            return word;

          

        }

每當我寫一些東西時，我都會得到這個作為輸出：我的字串你好我的字串

我的子字串方法是錯誤的，我該怎么做才能讓它只獲取我需要的部分并將其回傳？

uj5u.com熱心網友回復：

您可以使用我的方法（如果您只需要一個子字串方法）：

class Program
{
    static string CustomSubstring(string text, short startIndex, short indexInQuestion)
    {
        short i;
        for (i = startIndex; i < text.Length; i  ) ;
        StringBuilder Temp = new StringBuilder();
        //"StringBuilder.Append()" is faster than "string =string"
        //switch is faster than if
        switch (indexInQuestion < i)
        {
            case true:
                char[] C = text.ToArray();
                for (short j = startIndex; j <= indexInQuestion; j  )
                {
                    Temp.Append(C[j]);
                }
                break;
        }
        return Temp.ToString();
    }
    static void Main(string[] args)
    {
        Console.WriteLine(CustomSubstring("Merry Christmas", 6, 14));
        Console.ReadKey();
    }
}

輸出：圣誕節

uj5u.com熱心網友回復：

如果您想要一個接近您的解決方案，只需進行最少的更改，請考慮以下事項：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        static void Main()
        {
            Console.Write("Your string: ");
            string str = Console.ReadLine();                            // Console should be used only in the main part, not the methods
            Console.WriteLine(StringFuncs.Insert(str, "Hello", 5));
            Console.ReadKey();                                          // Waits for the user to press a key
        }
    }

    public class StringFuncs
    {
        /// <summary>
        /// Extracts a part of a string
        /// </summary>
        /// <param name="word"></param> The string you want an extraction from
        /// <param name="startIndex"></param>The position you want tthe extraction to start
        /// <param name="numberOfChars"></param>The number of chars to be extracted
        /// <returns></returns>
        public static string SubString(string word, int startIndex, int numberOfChars)
        {
            string result = "";                         // initialisation of the result string
            for (int i = 0; i < numberOfChars; i  )
            {
                result  = word[startIndex   i];         // adding chars one by one 
            }
            return result;                              
        }

        // the method below was detached from your old Insert method as it can be re-used
        /// <summary>
        /// Calculates the number of letter of a string
        /// </summary>
        /// <param name="word"></param>
        /// <returns></returns>
        public static int NumberOfLetters(string word)
        {
            int numberOfLetters = 0;
            foreach (char c in word)    // be explicite, specific and avoid the "var" thing
            {
                numberOfLetters  ;
            }
            return numberOfLetters;
        }

        /// <summary>
        /// Inserts a string into another one, at a given position
        /// </summary>
        /// <param name="targetString"></param>The string which will receive the second one
        /// <param name="insertString"></param>The string to be inserted in the first one
        /// <param name="insertPosition"></param>The position of insertion in the first string
        /// <returns></returns>
        public static string Insert(string targetString, string insertString, int insertPosition)
        {
            return SubString(targetString, 0, insertPosition)   insertString   SubString(targetString, insertPosition, NumberOfLetters(targetString) - insertPosition);
        }
    }
}

這不是對藝術大師處理和速度的爭論，而是展示了一種您可以在其他專案中重現的更具教學性的方法。我只是更喜歡可讀性和理解性。

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