Question

I have a class

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }   
}

List<Person> PersonList = new List<Perso>();
PersonList.Add(new Person() { FirstName = "aa", LastName = "AA" } );
PersonList.Add(new Person() { FirstName = "bb", LastName = "BB" } );

I’d like get a string with a comma separator for the LastName, using Linq, the result look like:
AA,BB

Thanks,

Answer 1

If you’re using .NET 4:

string lastNames = string.Join(",", PersonList.Select(x => x.LastName));

If you’re using .NET 3.5:

string lastNames = string.Join(",", PersonList.Select(x => x.LastName)
                                              .ToArray());

(Basically .NET 4 had some extra overloads added to string.Join.)