Question

My question is: What is the most efficient and correct, for large set of data ?

 _pointBuffer1 = new Point3DCollection {  
            new Point3D(140.961, 142.064, 109.300), new Point3D(142.728, 255.678, (...)

— or —

_pointBuffer1.Add(new Point3D(140.961, 142.064, 109.300)); _poitBuffer1.Add(142.728, (...)

Or is it the same ?

Point3D is declared as a Point3DCollection, but my question is for any object collection (could be Int32 for example) ..

Answer 1

Both are compiled to the same IL. Collection initializers are just syntactic sugar. They will call the Add method. Example:

var res = new List<int>() { 1, 2, 3 };

is compiled to:

List<int> <>g__initLocal0 = new List<int>();
<>g__initLocal0.Add(1);
<>g__initLocal0.Add(2);
<>g__initLocal0.Add(3);
List<int> res = <>g__initLocal0;

The only difference is an additional local variable being declared.