using System;

public class Program

{

    public static void Main()

    {

        var p = new Person { FirstName = "Rob", LastName = "Janssen" };

        Console.WriteLine(p.FullName);

    }

}

​

public class Person {

    public string FirstName {get;set;}

    public string LastName {get;set;}

    public string Infix {get;set;}

    public string FullName {

        get { return FirstName.SafeConcat(" ", Infix).SafeConcat(" ", LastName); }

    }

}

​

public static class MyStringExtensions {

    public static string SafeConcat(this string self, string separator, string value) {

        if (self == null)

            return value ?? string.Empty;

        return self + (value == null ? string.Empty : separator + value);

    }

}