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Quote: "4. Flexible array members ..... int elems[]; // <-- flexible array member" TIL that a dynamic array is also called flexible. This generation, out of bo

Quote: "4. Flexible array members ..... int elems[]; // <-- flexible array member" TIL that a dynamic array is also called flexible. This generation, out of boringness, is trying to redefine well established paradigms? Because, for me, a 90's formed developer, "flexible" means maybe inheritance, or even better polymorphism. There is nothing flexible about a dynamic array. Its structure is well defined in the stack/heap, and with current compiler optimizations can even be demoted to a simple static array for faster access within CPU registries.

Jorengarenar 4y ago
"Dynamic array" refers to block of memory allocated via malloc() which you just happen to use as array. "Flexible array member" [0] is when you have a struct and its last member is an array with unspecified size. An example: #include <stdio.h> #include <stdlib.h> struct Foo { int len; int* arr; // dynamic "array" }; struct Bar { int len; int arr[]; // FAM }; int main() { const int n = 12; // have to allocate myself; no guarante it will be nearby the rest of struct struct Foo* a = malloc(sizeof a); a->arr = malloc(n * sizeof *(a->arr)); // array is part of the memory allocated for struct struct Bar* x = malloc((sizeof x) + n*(sizeof *(x->arr))); return 0; } [0]: https://en.wikipedia.org/wiki/Flexible_array_member https://en.wikipedia.org/wiki/Flexible_array_member
- unnouinceput 4y ago
  >"Dynamic array" refers to block of memory allocated via malloc() which you just happen to use as array.< No. A dynamic array is an array which can be expanded or shrinked during its runtime life. The fact that C/C++ uses malloc for that (and btw, it's not the only way to do it) it's her problem. In other languages you have dynamic arrays that can be expanded/shrinked without using an extra line - main reason why nowadays Rust is a replacement for C/C++ >[0]< From you own wiki reference: "the flexible array member must be last" LMAO, really? Well, that indeed is a bigger C quirk. In Pascal, as an example, I can have it anywhere inside the record (struct equivalent of C), and it can be just as "flexible".
  - blep_ 4y ago
    It has to be last because it's not a pointer to the array, it is the array. The array elements are immediately after the struct in memory. You can't resize it without reallocating the whole struct.

Jorengarenar 4y ago

"Dynamic array" refers to block of memory allocated via malloc() which you just happen to use as array. "Flexible array member" [0] is when you have a struct and its last member is an array with unspecified size. An example: #include <stdio.h> #include <stdlib.h> struct Foo { int len; int* arr; // dynamic "array" }; struct Bar { int len; int arr[]; // FAM }; int main() { const int n = 12; // have to allocate myself; no guarante it will be nearby the rest of struct struct Foo* a = malloc(sizeof a); a->arr = malloc(n * sizeof *(a->arr)); // array is part of the memory allocated for struct struct Bar* x = malloc((sizeof x) + n*(sizeof *(x->arr))); return 0; } [0]: https://en.wikipedia.org/wiki/Flexible_array_member https://en.wikipedia.org/wiki/Flexible_array_member

unnouinceput 4y ago
>"Dynamic array" refers to block of memory allocated via malloc() which you just happen to use as array.< No. A dynamic array is an array which can be expanded or shrinked during its runtime life. The fact that C/C++ uses malloc for that (and btw, it's not the only way to do it) it's her problem. In other languages you have dynamic arrays that can be expanded/shrinked without using an extra line - main reason why nowadays Rust is a replacement for C/C++ >[0]< From you own wiki reference: "the flexible array member must be last" LMAO, really? Well, that indeed is a bigger C quirk. In Pascal, as an example, I can have it anywhere inside the record (struct equivalent of C), and it can be just as "flexible".
- blep_ 4y ago
  It has to be last because it's not a pointer to the array, it is the array. The array elements are immediately after the struct in memory. You can't resize it without reallocating the whole struct.