C#•2y ago

❔ Create list from items and other lists

Whats the best way to create a new list that combines an item A, an item B, and a list C?

11 Replies

DyadOP•2y ago

something like?

var r = new []
{
  new [] { A },
  new [] { B },
  C
}
.SelectMany(x => x);

var r = new []
{
  new [] { A },
  new [] { B },
  C
}
.SelectMany(x => x);

Jimmacle•2y ago

you could use the .Concat extension method on the list C.Concat(new [] { A, B }) but if your goal is a new list then just copy the list and add the items

var newList = new List<MyObject>(C);
newList.Add(A);
newList.Add(B);

var newList = new List<MyObject>(C);
newList.Add(A);
newList.Add(B);

DyadOP•2y ago

I guess I should have clarified the order matters

Jimmacle•2y ago

then

var newList = new List<MyObject> { A, B };
newList.AddRange(C);

var newList = new List<MyObject> { A, B };
newList.AddRange(C);

DyadOP•2y ago

gotcha I often try to write my code in a way that declaration and assignment all happens in a single line I think in javascript you can do new [a, b, ...c], was hoping there was something similar in c#

Jimmacle•2y ago

nope, no spread operator in C#

DyadOP•2y ago

gotcha. thank you 🙂

Sun「無用」•2y ago

spread operator is just sugar to what AddRange would be in c#

Jimmacle•2y ago

basically there's just no one-liner for this specific application

Thinker•2y ago

coming soon™!

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Create list from items and other lists