using System;

using SmartFormat;

​

public class Point

{

    public double? Lat { get; set; }

    public double? Lon { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var point = new Point {Lat = 23.45};

        Console.WriteLine(Smart.Format("Latitude: {Lat:choose(null):N/A|{}}, longitude: {Lon:choose(null):N/A|{}}", point));

        // Output is:

        // Latitude: N/A, longitude: N/A

        // Output I want is:

        // Latitude: 23.45, longitude: N/A

    }

}