title: fstream.open() not appending to existing file
body: <p>Here is my main function:</p>
  
  <pre><code>void main()
  
  {
      Student s1 = Student(12, "Ali");
      Student s2 = Student(1, "Hassan");
      Student s3 = Student(8, "Bilal");
  
      s1.WriteFile();
      s2.WriteFile();
      s3.WriteFile();
  }
  </code></pre>
  
  <p>while WriteFile() function is:</p>
  
  <pre><code>void WriteFile()
  
      {
          fstream fileWriter, fileReader;
  
      string string_line;
  
      fileWriter.open("D:\A111.txt");
  
      while (!std::getline(fileReader, string_line).eof())
      {
  
      }
  
      cout &lt;&lt; GetRoll_No() &lt;&lt; " , " &lt;&lt; GetName() &lt;&lt; endl;
  
      fileWriter &lt;&lt; GetRoll_No() &lt;&lt; " , " &lt;&lt; GetName() &lt;&lt; endl;
  
      fileWriter.close();
      fileReader.close();
  }
  </code></pre>
  
  <p>Whenever I call it, it only shows me following in A111.txt</p>
  
  <p>8 , Bilal</p>
  
  <p>So why doesn't it append it at the end of existing file. Please note that filereader is added only later on while trying for a solution, it gives same error without eof() as well</p>