C＃从StringBuilder的开头提取数据

Question

I want to extract some chars from start of StringBuilder variable.
I wrote bellow code :

private string getPart(StringBuilder data, int len)
{
    string s = data.ToString(0, len);
    data.Remove(0, len);
    return s;
}

Any suggestion fro better coding?

Answer 1

If you want character extraction in many parts of your code, you can try implementing the algorithm as an extension method :

  public static class StringBuilderExtensions {
    public static String Extract(this StringBuilder source, int length) {
      if (Object.ReferenceEquals(null, source))
        throw new ArgumentNullException("source");
      else if ((length < 0) || (length > source.Length))
        throw new ArgumentOutOfRangeException("length");

      // Your actual algorithm
      String result = source.ToString(0, length);

      source.Remove(0, length);

      return result;
    }
  }

  ...

  StringBuilder data = ...
  String s = data.Extract(len); // <- Just extract

Answer 2

You can use CopyTo method:

private string getPart(StringBuilder data, int len)
{
    var output = new char[len];
    data.CopyTo(0, output, 0, len);
    data.Remove(0, len);
    return new string(output);
}