C#自定义字符串替换Replace方法实例

public static string Replace(string originalString, string strToBeReplaced, string strToReplace)
{
    string resultString = null;
    char[] originalCharArray = originalString.ToCharArray();
    char[] strToBeCharArray = strToBeReplaced.ToCharArray();
    char[] strToCharArray = strToReplace.ToCharArray();
    List<Char> newCharList = new List<Char>();

    for (int i = 0; i < originalCharArray.Count(); i++)
    {
 if (originalCharArray[i] == strToBeCharArray[0])
 {
     bool IsReplace = false;
     for (int j = 0; j < strToBeCharArray.Count(); j++)
     {
  if (((i + j) < originalCharArray.Count())
      && (originalCharArray[i + j] == strToBeCharArray[j]))
  {
      IsReplace = true;
  }
  else
  {
      IsReplace = false;
      break;
  }
     }
     if (IsReplace)
     {
  i += strToBeCharArray.Count() - 1;
  for (int k = 0; k < strToCharArray.Count(); k++)
  {
      newCharList.Add(strToCharArray[k]);
  }
     }
     else
     {
  newCharList.Add(originalCharArray[i]);
     }
 }
 else
 {
     newCharList.Add(originalCharArray[i]);
 }
    }

    resultString = string.Join("", newCharList);
    return resultString;
}

public class Replace
{
        /// <summary>
        /// Replace 方法
        /// </summary>
        /// <param name="source">原字符串</param>
        /// <param name="find">需要查找的字符串</param>
        /// <param name="replace">替换的字符串</param>
        /// <returns>最终替换成功的字符串</returns>
        public string Replace(string source, string find, string replace)
        {
            // 要查找的字符串大于原来字符串,则不处理，返回原来字符
            if (find.Length > source.Length)
            {
                return source;
            }

            // 记录找到多少次
            int findCount = 0;
            // 仅用于标记，辅助记录多少次
            bool flag = true;
            // n：source字符串遍历的数值；j：find字符串遍历的数值
            int n = 0, j = 0;
            // s：查找到字符串的开始索引，e：查找到字符串的结束索引
            int s = 0, e = 0;

            while (true)
            {
                // 判断字符是否相等
                if (source[n] == find[j])
                {
                    // Source 序列+1
                    n++;
                    // 判断是否为第一位相匹配
                    if (j == 0)
                    {
                        // 赋值给s，查找到头的索引
                        s = n;
                    }
                    // 查找到后下一次比较find的下一位
                    j++;
                    // 标记暂时找到前面相同的字符
                    flag = true;
                }
                else
                {
                    // 记录不完全匹配
                    flag = false;
                    // find的索引归零
                    j = 0;
                    // Source的索引继续想加
                    n++;
                }

                // 已经查找完毕
                if (j == find.Length)
                {
                    // 完全匹配
                    if (flag)
                    {
                        // 查找的字符数量+1
                        findCount++;
                    }
                    // 记录查找的数组结尾索引
                    e = n;
                    // source 索引继续+1
                    n++;
                    // find的索引归零
                    j = 0;
                    // 计算生成新字符串，之后继续循环，直到替换所有字符串
                    source = GetNewString(source, find, replace, s, e);
                }
                // Source遍历完毕，则退出循环
                if (n >= source.Length)
                {
                    break;
                }
            }
            // 最终字符串
            return source;
        }

        /// <summary>
        /// 获得新的字符串
        /// </summary>
        /// <param name="source">源字符串</param>
        /// <param name="find">需要查找的字符</param>
        /// <param name="replace">需要替换的字符</param>
        /// <param name="startIndex">查找到的字符开始索引</param>
        /// <param name="endIndex">查找到的字符结束索引</param>
        /// <returns>返回替换后的字符串</returns>
        public string GetNewString(string source, string find, string replace, int startIndex, int endIndex)
        {
            // 新字符串的长度
            int newArrayLength = source.Length + endIndex - startIndex;
            // 新字符数组
            char[] newStringArray = new char[newArrayLength];
            // 将前半部分复制给新字符串
            for (int i = 0; i < startIndex - 1; i++)
            {
                newStringArray[i] = source[i];
            }
            // 当前临时开始索引
            int tempCurrentStartLength = startIndex - 1;
            // 将需要替换的赋值给新的字符数组
            for (int i = tempCurrentStartLength; i < tempCurrentStartLength + replace.Length; i++)
            {
                newStringArray[i] = replace[i - tempCurrentStartLength];
            }
            // 将之后剩余的字符赋值给新的数组
            for (int i = endIndex + 1; i < newArrayLength; i++)
            {
                newStringArray[i] = source[i - 1];
            }
            // 返回转换后的字符串
            return string.Concat(newStringArray);
        }
}