Collection to string using linq

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.)

Answer 2

You can use

PersonList.Select(p => p.LastName).Aggregate((s1,s2) => s1 + ", " + s2);