LINQ list to sentence format (insert commas & “and”)

Question

I have a linq query that does something simple like:

var k = people.Select(x=>new{x.ID, x.Name});

I then want a function or linq lambda,

Answer 1

Just for fun, here’s something that really uses functional LINQ — no loop and no StringBuilder. Of course, it’s pretty slow.

var list = new[] { new { ID = 1, Name = "John" },
                   new { ID = 2, Name = "Mark" },
                   new { ID = 3, Name = "George" } };

var resultAggr = list
    .Select(item => item.ID + ":" + item.Name)
    .Aggregate(new { Sofar = "", Next = (string) null },
               (agg, next) => new { Sofar = agg.Next == null ? "" :
                                            agg.Sofar == "" ? agg.Next :
                                            agg.Sofar + ", " + agg.Next,
                                    Next = next });
var result = resultAggr.Sofar == "" ? resultAggr.Next :
             resultAggr.Sofar + " and " + resultAggr.Next;

// Prints 1:John, 2:Mark and 3:George
Console.WriteLine(result);