StreamReader sr = new StreamReader("C:\\1.txt");
String line = sr.ReadLine();
textBox1.Text = line;
sr.Close();

StreamWriter sw = new StreamWriter("C:\\2.txt");
String line = textBox1.Text;
sw.WriteLine(line);
sw.Close();

 
using System;
using System.IO;
using System.Collections;    namespace TextFileReaderAndWriter_csharp
{
        /// 

        /// Summary description for Class1.
        /// 
        class Class1
        {
                static void Main(string[] args)
                {
                        //文字檔讀取
                        StreamReader objReader = new StreamReader("test.txt");
                        string sLine="";
                        ArrayList arrText = new ArrayList();                            while (sLine != null)
                        {
                                sLine = objReader.ReadLine();
                                if (sLine != null)
                                        arrText.Add(sLine);
                        }
                        objReader.Close();
            
                        //文字檔寫入
                        StreamWriter objWriter = new StreamWriter(File.Create("test2.txt"));                            foreach (string sOutput in arrText)
                         objWriter.WriteLine(sOutput);
                         
                        objWriter.Close();                         
                        
                }
        }
}    

sline='';
while sline <> nil do
begin
  sline:=r.readline;
  if sline <> nil
      arrtext.add(sline);
end;