How and when to abandon the use of arrays in C#?

Question

I\'ve always been told that adding an element to an array happens like this:

An empty copy of the array+1element is created and then the data from t

Answer 1

This really depends on what you mean by "add."

If you mean:

T[] array;
int i;
T value;
...
if (i >= 0 && i <= array.Length)
    array[i] = value;

Then, no, this does not create a new array, and is in-fact the fastest way to alter any kind of IList in .NET.

If, however, you're using something like ArrayList, List, Collection, etc. then calling the "Add" method may create a new array -- but they are smart about it, they don't just resize by 1 element, they grow geometrically, so if you're adding lots of values only every once in a while will it have to allocate a new array. Even then, you can use the "Capacity" property to force it to grow before hand, if you know how many elements you're adding (list.Capacity += numberOfAddedElements)