Item — HN Reader

Yes, pointer + plus length is something else.

C has variably modified types (in CS usually known as dependent types), where the length is encoded into the type. A VLA has a dependent type: char buf[n] or a pointer to a VLA has: char (*buf)[n]. This is super powerful and theoretically sound concept although not yet really exploited in C. But the bound travels with the type and you can get bounds checking at run-time:

char buf[n]; auto foo = &buf; buf[n] = 1; // run-time bounds check possible

Pascal, Ada, Fortran, D have VLAs and certainly more languages have VLAs.

1 comments

I don't think D has VLAs.

Between the fact that most modern languages don't have VLAs and that the languages you mention are most certainly not modern, your statement of: "Also note that most other languages except C++ also have VLAs." is not even close to correct.

D has dynamic arrays which can be on the stack. At least it looks to me like this: https://godbolt.org/z/vTqMah569

I guess this depends on whether you count higher level languages with GC which often have some kind of automatically managed dynamic array / vector type but not necessarily call them VLAs.

I also did not say "modern" - not that this is clearly defined. If you only count Zig and Rust as modern, then those two do not have VLAs as far as I know. But this was not my main point anyway.