It’s actually the statement after the one you mark as causing the program to crash that causes the program to crash! You must pass the same pointer to delete[] as you get back from new[]. Otherwise the behaviour of the program is undefined.
Once free()-d, I am expecting program’s virtual memory (VIRT) consumption to be down by 1MB. Well, this is not guaranteed by the C standard. It only says, once you free() the memory, you should not be accessing that any more. Whether the memory block is actually returned to the available memory pool or kept aside … Read more
Warning: the code here only showcases the storage aspect, it is a skeleton, no dynamic aspect (construction, copy, move, destruction) has been taken into account. I would suggest an approach using the C++0x new class aligned_storage, which is precisely meant for having raw storage. // header class Foo { public: private: struct Impl; Impl& impl() … Read more
On Linux mmap2 is a sensible system call to use for this at a low level. It takes 6 arguments, so in IA32 you can call it using: mov eax, 192 ; mmap2 xor ebx, ebx ; addr = NULL mov ecx, 4096 ; len = 4096 mov edx, $7 ; prot = PROT_READ|PROT_WRITE|PROT_EXEC mov … Read more
You need to use dynamic memory when: You cannot determine the maximum amount of memory to use at compile time; You want to allocate a very large object; You want to build data structures (containers) without a fixed upper size; You don’t always know how much memory you will need to set aside at compile … Read more
Your requirements are exactly those of std::list, except that you’ve decided you don’t like the overhead of node-based allocation. The sane approach is to start at the top and only do as much as you really need: Just use std::list. Benchmark it: is the default allocator really too slow for your purposes? No: you’re done. … Read more
Note that whilst a Cat is an Animal, an array of Cats is not an array of Animals. In other words, arrays are invariant in C++, not covariant like they are in some other languages. So you are up-casting this array and this later confuses the compiler. You must do array delete[] in this case … Read more
Intel compilers support POSIX (Linux) and non-POSIX (Windows) operating systems, hence cannot rely upon either the POSIX or the Windows function. Thus, a compiler-specific but OS-agnostic solution was chosen. C11 is a great solution but Microsoft doesn’t even support C99 yet, so who knows if they will ever support C11. Update: Unlike the C11/POSIX/Windows allocation … Read more
Ultimately, no. Polymorphism only works with non-value types: references and pointers. And since references can only be bound once, you cannot really use them in standard containers. That leaves you with pointers. You’re attacking the problem at the wrong end. If you are concerned about the overhead of allocating lots of small objects (and I’m … Read more
Yes, automatic variables will be destroyed at the end of the enclosing code block. But keep reading. Your question title asks if a destructor will be called when the variable goes out of scope. Presumably what you meant to ask was: will Foo’s destructor be called at the end of main()? Given the code you … Read more