C#中 如何读取TXT文件第N行内容

Question

C#中 如何读取TXT文件第N行内容
   或第N行后的关键字怎么取

Answer 1

使用下面这个函数
filename===要读的文件名
startline===从第几行开始读
linecount===要读的总行数，如果<1,视为读到文件末尾        private string ReaderLinesFromFile(string filename,int startLine,int linecount)
        {
            int i = 0;
            StringBuilder sb = new StringBuilder();            StreamReader reader = new StreamReader(filename);
            while (!reader.EndOfStream)
            {
                if (i >= startLine)
                {
                    if (linecount < 1)
                        sb.Append(reader.ReadToEnd());
                    else
                        sb.Append(reader.ReadLine());
                }
                else
                    reader.ReadLine();
                i++;
                if (i >= linecount + startLine) break;
            }
            reader.Close();
            reader.Dispose();
            return sb.ToString();
        }

Answer 2

private string ReaderLinesFromFile(string filename,int startLine)
        {
            int i = 0;
            StringBuilder sb = new StringBuilder();            StreamReader reader = new StreamReader(filename);
            while (!reader.EndOfStream)
            {
                if (i >= startLine)
                {
                   
                        sb.Append(reader.ReadLine());
                }
                else
                    reader.ReadLine();
                i++;
                
            }
            reader.Close();
            reader.Dispose();
            return sb.ToString();
        }
  这样好象 也可以

Answer 3

           int n = 3;
            string[] str = File.ReadAllLines(Server.MapPath("txttxt.txt"));
            if (n < str.Length)
                Response.Write(str[3]);
            else
                Response.Write("超出行数");

Answer 4

要获取第n行之后的话
一个循环+索引判断是否大于要读取的行数
在stringbuilder.append