使用自定义的行分隔符，从StreamReader中读取一行字符串

using System;
using System.IO;
using System.Text;

namespace NetCoreReadline
{
    /// <summary>
    /// StreamReader扩展类
    /// </summary>
    public static class StreamReaderExtension
    {
        /// <summary>
        /// 使用自定义的行分隔符，从StreamReader中读取一行字符串
        /// </summary>
        /// <param name="streamReader">StreamReader类对象实例</param>
        /// <param name="delimiter">自定义的行分隔符</param>
        /// <returns>从StreamReader中读取的一行字符串</returns>
        public static string ReadLineWithDelimiter(this StreamReader streamReader, string delimiter)
        {
            StringBuilder sb = new StringBuilder();
            bool found = false;

            while (!found && !streamReader.EndOfStream)
            {
                for (int i = 0; i < delimiter.Length; i++)
                {
                    char c = (char)streamReader.Read();//如果StreamReader采用的是支持中文的编码，例如Encoding.UTF8，那么这里读取到的字符char类型也会是中文，不会是乱码
                    sb.Append(c);

                    if (c != delimiter[i])
                        break;

                    //表示读取到一个完整的行分隔符了
                    if (i == delimiter.Length - 1)
                    {
                        sb.Remove(sb.Length - delimiter.Length, delimiter.Length);
                        found = true;
                    }
                }
            }

            return sb.ToString();
        }
    }


    class Program
    {
        static void Main(string[] args)
        {
            string filepath = AppDomain.CurrentDomain.BaseDirectory + "Data\\RawData.txt";

            using (StreamReader streamReader = new StreamReader(filepath, Encoding.UTF8))
            {
                while (!streamReader.EndOfStream)
                {
                    string lineText = streamReader.ReadLineWithDelimiter("||");//定义"||"为行分隔符

                    Console.WriteLine("StreamReader 读到一行字符串：\"{0}\"", lineText);
                }
            }

            Console.WriteLine("按任意键结束程序...");
            Console.ReadKey();
        }
    }
}

昨天天气不错ABC||今天天气不错EFG||明天天气不错HIJ