Programs Knowledge

if (!System.IO.File.Exists(path))
{
    //create file
    using (System.IO.FileStream fs = System.IO.File.Create(path))
        fs.Close();//release resource
}

System.IO.StreamWriter file = new System.IO.StreamWriter(path, true);//true表示不覆蓋data
file.WriteLine("log...");//write data
file.WriteLine("------------------------------------------------");//分隔線
file.Close();

if (!System.IO.File.Exists(path))//若沒有該檔案救create
{
    System.IO.FileStream fs = System.IO.File.Create(path);
    fs.Close();//release resource
}

using (System.IO.StreamWriter sw = System.IO.File.AppendText(path))
{
    sw.Write("...");//不換行寫入String
    sw.WriteLine("...");//換行寫入String
    sw.WriteLine("-------------------------------------------");//分隔線
    sw.Flush();
    sw.Close();//release resource
}

{
    string files = string.Empty;
    string filePath = System.Environment.CurrentDirectory + "\\test.txt";//webform: Server.MapPath("~")+"\\folder\\test.txt";

    if (System.IO.File.Exists(filePath))
    {
        using (System.IO.StreamReader sr = new System.IO.StreamReader(filePath))
        {
            string line = string.Empty;

            while (!string.IsNullOrEmpty(line = sr.ReadLine()))
                files += line + ", ";//抓出每一行以逗點隔開
        }
    }

    return files;
}