For types for which such cast is permitted (e.g. if T1 is a POD-type and T2 is unsigned char), the approach with static_cast is well-defined by the Standard. On the other hand, reinterpret_cast is entirely implementation-defined – the only guarantee that you get for it is that you can cast a pointer type to any … Read more
The two concepts are orthogonal: A void pointer, (void *) is a raw pointer to some memory location. A null pointer is a special pointer that doesn’t point to anything, by definition. It can be a pointer to any type, void or otherwise. A void pointer can be null or not: void *void_ptr1 = nullptr; … Read more
While it might be tempting to conclude that all pointers are the same size because “pointers are just addresses, and addresses are just numbers of the same size”, it is not guaranteed by the standard and thus cannot be relied upon. The C++ standard explicitly guarantees that: void* has the same size as char* ([basic.compound]/5) … Read more
Is it a good idea to use intptr_t as a general-purpose storage (to hold pointers and integer values) instead of void*? No. intptr_t is not guaranteed to exist. First, as you note, it was introduced in C99. Second, implementations are not required to have an integer type big enough to hold converted pointer values without … Read more
0xffffffff is technically a valid address in a 32 bit environment but on most operating systems (Certainly Linux/Windows) will be in the reserved kernel part of the address space. That means that in user mode processes it’s safe to use it as a error code since no user mode allocation function would return this as … Read more
You can cast it to an intptr_t type. It’s an int type guaranteed to be big enough to contain a pointer. Use #include <cstdint> to define it.
In C, pointer conversions to and from void* were always implicit. In C++, conversions from T* to void* are implicit, but void* to anything else requires a cast.
Is it possible to dereference the void pointer without type-casting in C programming language… No, void indicates the absence of type, it is not something you can dereference or assign to. is there is any way of generalizing a function which can receive pointer and store it in void pointer and by using that void … Read more
void * means “a reference to some random chunk o’ memory with untyped/unknown contents” id means “a reference to some random Objective-C object of unknown class” There are additional semantic differences: Under GC Only or GC Supported modes, the compiler will emit write barriers for references of type id, but not for type void *. … Read more
Deleting via a void pointer is undefined by the C++ Standard – see section 5.3.5/3: In the first alternative (delete object), if the static type of the operand is different from its dynamic type, the static type shall be a base class of the operand’s dynamic type and the static type shall have a virtual … Read more