File Stream C#

using System;
using System.IO;
public class SWBuff 
{
    public static void Main(String[] args)
    {
            string logFile = "a.log";
            string fileName = "a.log";
      string textToAdd = "asdf";
          
            StreamWriter swFromFileTrue = new StreamWriter(fileName,true);
            swFromFileTrue.Write(textToAdd);
            swFromFileTrue.Flush();
            swFromFileTrue.Close();
    }
}