<i>On the other hand, C's treatment of arrays in general (not just strings) has unfortunate implications both for optimization and for future extensions. The prevalence of pointers in C programs, whether those declared explicitly or arising from arrays, means that optimizers must be cautious, and must use careful dataflow techniques to achieve good results. Sophisticated compilers can understand what most pointers can possibly change, but some important usages remain difficult to analyze. For example, functions with pointer arguments derived from arrays are hard to compile into efficient code on vector machines, because it is seldom possible to determine that one argument pointer does not overlap data also referred to by another argument, or accessible externally. More fundamentally, the definition of C so specifically describes the semantics of arrays that changes or extensions treating arrays as more primitive objects, and permitting operations on them as wholes, become hard to fit into the existing language.</i><p>Ritchie notes the difficulty with optimization and aliasing and as far as I know the only portable C89/99 convention for this is using the appropriate function if what you want to do is memcpy() or memmove().<p>I love C and programming is mostly a hobby for me. But my language experience does not really extend beyond C and C++, other than reading about D, Lisp, Rust, etc. I also think the STL is the beautiful thing C++ gave us, and having it as a library is better than building these structures into the language. The STL relies heavily on iterators of course.<p>My question to HN is: do any languages that really emphasize pointers and iterators over arrays and indices have a non-cumbersome way of telling the compiler when no aliasing is expected? As a hobbyist, I am more interested in something like slices from D or parameter type restrictions than trivially obvious global guarantees like ``if you mutably borrow it then there is no aliasing''. Do D programmers find the slices helpful and easy? Is the syntax and/or semantics such that the programmer can provide the compiler with aliasing info? Are there a small number of type concepts for this or does it explode with the number of different data structures.<p>I know there is the restrict keyword, but I have always been too lazy to use it in C and even in C++ it seems (quadratically?) unlikely you would be energetic enough to properly declare which pairs of entities could not alias.