title: String does not contain a definition for add method
body: <p>I am doing a program in .NET. I am doing some changes in the program. I am getting a error </p>
  
  <blockquote>
    <p>String does not contain a definition for add method.</p>
  </blockquote>
  
  <p>I don know how to rectify this error.</p>
  
  <pre><code>private string process(string fname)
  {
    //string errs = "";
    string Strings = "";
    string[] lines = File.ReadAllLines(fname);
    StringBuilder b = new StringBuilder();
    for (int i = 1; i &lt; lines.Length; i++)
    {
      string[] sa = lines[i].Split(new string[] { "," }, StringSplitOptions.None);
      bool ok = false;
      if (sa[1].CompareTo("EQ") == 0)
        ok = true;
      if (!ok &amp;&amp; sa[1].CompareTo("BE") != 0)
        continue;
      string name = sa[0];
      int token = NSECM.Lookup(name);
      if (token == 0)
      {
        //errs += "Symbol " + name + " not found\r\n";
        continue;
      }
      //int open = (int)(double.Parse(sa[2]) * 100 + 0.5);
      //int high = (int)(double.Parse(sa[3]) * 100 + 0.5);
      //int low = (int)(double.Parse(sa[4]) * 100 + 0.5);
      //int close = (int)(double.Parse(sa[5]) * 100 + 0.5);
      //uint vol = uint.Parse(sa[8]);
      //int date = cdate(sa[10]);
      //uint time = cvt(date);
      uint open = (uint)(double.Parse(sa[2]) * 100 + 0.5);
      uint high = (uint)(double.Parse(sa[3]) * 100 + 0.5);
      uint low = (uint)(double.Parse(sa[4]) * 100 + 0.5);
      uint close = (uint)(double.Parse(sa[5]) * 100 + 0.5);
      uint vol = uint.Parse(sa[8]);
      int date = cdate(sa[10]);
      //b.Append("D");
      b.Append("S" + (1000000 + token).ToString().Substring(1));
      b.Append("-" + date);
      b.Append("|D");
      b.Append(Encode.encode6(cvt(date)));
      //b.Append(Encode.encode6(time));
      b.Append(Encode.encode4(open));
      b.Append(Encode.encode4(high));
      b.Append(Encode.encode4(low));
      b.Append(Encode.encode4(close));
      b.Append(Encode.encode6(vol));
      //b.Append("\n");
      Strings.Add(b.ToString());
    }  
  }  
  </code></pre>