Pointers vs functional or array semantics

[data pulverizer via Digitalmars-d-learn]

On Saturday, 25 February 2017 at 11:15:53 UTC, ketmar wrote:
> data pulverizer wrote:
>
>> I have noticed that some numerical packages written in D use 
>> pointer semantics heavily (not referring to packages that link 
>> to C libraries). I am in the process of writing code for a 
>> numerical computing library and would like to know whether 
>> there times when addressing an array using pointers conveys 
>> performance benefits over using D's array or functional 
>> semantics?
>
> using `arr.ptr[n]` instead of `arr[n]` bypasses bounds 
> checking. this may be diserable in tight loops (while disabling 
> bounds checking globally is not).
>
> but note that `foreach (int n; arr)` doesn't do bounds checking 
> in loop too (afair), so you prolly better use `foreach` instead 
> of pointers. this way your code will be fast, but still safe.

Thanks ketmar and thanks in advance to anyone else that comments.