On Wed, Jun 21, 2023 at 02:09:26AM +0000, Cecil Ward via Digitalmars-d-learn wrote: > First is an easy one: > > 1.) I have a large array and a sub-slice which I want to set up to be > pointing into a sub-range of it. What do I write if I know the start > and end indices ? Concerned about an off-by-one error, I have > start_index and past_end_index (exclusive).
array[start_idx .. one_past_end_idx] > 2.) I have a dynamic array and I wish to preinitialise its alloc cell > to be a certain large size so that I don’t need to reallocate often > initially. I tell myself that I can set the .length property. Is that > true? You can use `array.reserve(preinitSize);`. > 2a.) And what happens when the cell is extended, is the remainder > zero-filled or remaining full of garbage, or is the size of the alloc > cell something separate from the dynamic array’s knowledge of the > number of valid elements in it ? The size of the allocated cell is managed by druntime. On the user code side, all you know is the slice (start pointer + length). The allocated region outside the current array length is not initialized. Assigning to array.length initializes the area that the array occupies after the length has been extended. T -- Ph.D. = Permanent head Damage