using (StreamWriter w = File.AppendText("myFile.txt"))
{
  w.WriteLine("hello");
}

文件。AppendText会这样做:

using (StreamWriter w = File.AppendText("textFile.txt")) 
{
    w.WriteLine ("-------HURRAY----------");
    w.Flush();
}

你可以看看TextWriter类。

//Open File
TextWriter tw = new StreamWriter("file.txt");

//Write to file
tw.WriteLine("test info");

//Close File
tw.Close();

using (StreamWriter w = File.AppendText("myFile.txt"))
{
  w.WriteLine("hello");
}

//display sample reg form in notepad.txt
using (StreamWriter stream = new FileInfo("D:\\tt.txt").AppendText())//ur file location//.AppendText())
{
   stream.WriteLine("Name :" + textBox1.Text);//display textbox data in notepad
   stream.WriteLine("DOB : " + dateTimePicker1.Text);//display datepicker data in notepad
   stream.WriteLine("DEP:" + comboBox1.SelectedItem.ToString());
   stream.WriteLine("EXM :" + listBox1.SelectedItem.ToString());
}

或者您可以使用File。AppendAllLines(字符串,IEnumerable <字符串>)

File.AppendAllLines(@"C:\Path\file.txt", new[] { "my text content" });