Convert items in List<> to a concatenated and formatted string?

Question

Given:

    protected class Marker { 
        public string Name { get; set; }
        public string Lat { get; set; }
        public string Long { get; set; } 
    };

List<Marker> allMarkers = new List<Marker>();
allMarkers.Add(new Marker{Name="Bondi Beach", Lat = "-33.890542", Long = "151.274856"});
allMarkers.Add(new Marker{Name="Coogee Beach", Lat = "-33.923036", Long = "151.259052"});
allMarkers.Add(new Marker{Name="Cronulla Beach", Lat = "-34.028249", Long = "151.157507"});
allMarkers.Add(new Marker{Name="Manly Beach", Lat = "-33.800101", Long = "151.287478"});
allMarkers.Add(new Marker{Name="Maroubra Beach", Lat = "-33.950198", Long = "151.259302"});

I'd like to convert to a string in this format:

['Bondi Beach', -33.890542, 151.274856],
['Coogee Beach', -33.923036, 151.259052],
['Cronulla Beach', -34.028249, 151.157507],
['Manly Beach', -33.800101, 151.287478],
['Maroubra Beach', -33.950198, 151.259302]

Is there a one liner way to do this, something similar to string.Join(), or do I have to do it manually via a foreach on the List and use stringbuilder.appendformat()?

Answer 1

If Marker is your own class, consider overriding the ToString() method to display each line the way you do. Then, you can use a simple String.Join() to combine it all together.

protected class Marker
{
    public string Name { get; set; }
    public string Lat { get; set; }
    public string Long { get; set; }
    public override string ToString()
    {
        return String.Format("['{0}', {1}, {2}]", Name, Lat, Long);
    }
};

Then, to use:

List<Marker> allMarkers = new List<Marker>();
allMarkers.Add(new Marker { Name = "Bondi Beach", Lat = "-33.890542", Long = "151.274856" });
allMarkers.Add(new Marker { Name = "Coogee Beach", Lat = "-33.923036", Long = "151.259052" });
allMarkers.Add(new Marker { Name = "Cronulla Beach", Lat = "-34.028249", Long = "151.157507" });
allMarkers.Add(new Marker { Name = "Manly Beach", Lat = "-33.800101", Long = "151.287478" });
allMarkers.Add(new Marker { Name = "Maroubra Beach", Lat = "-33.950198", Long = "151.259302" });
Console.Write(String.Join(",\n", allMarkers));

Note: If you are dealing with a lot of markers and notice bad performance, consider rewriting that String.Format() line as:

return "['" + Name + "', " + Lat.ToString() + ", " + Long.ToString() + "]";

You may notice this is better (or worse), depending on your use case.

Answer 2

By using extension methods, you can do something like this

static class Extensions
{
   static string ToStringAll(this List<Marker> markers)
   {
      string all = "";

      foreach (var marker in markers)
      {
         all += marker.ToString() + ",";
      }

      return all.Trim(',');
   }
}

Then all you need to use in the future is

allMarkers.ToStringAll();

Answer 3

You can use String.Join and a simple LINQ Select to project them to the format you wish ...

   allMarkers.Select(m => "['" + m.Name + "', " + m.Lat + ", " + m.Long + "]")

BUT You might instead want to consider serializing your data to JSON using DataContract serialization rather than inventing your own serialized object notation.