如何通过std :: vector <void*> *作为std :: vector <MyStruct*> *功能

Question

How to pass std::vector<void*> * as std::vector<MyStruct*>* to a function?

The function declaration is void SetDataReferences(std::vector<MyStruct*>* pVector);

if I pass std::vector<void*> * as std::vector<MyStruct*>* I am getting below error

error C2664: 'CTagFilterComboBox::SetDataReferences' : cannot convert parameter 2 from ' std::vector<_Ty> * ' to ' std::vector<_Ty> * '

How to resolve this?

Answer 1

Unfortunately std::vector<void*> is a completely different type to std::vector<MyStruct*>* , so no cast is going to work.

You need to rebuild the vector from scratch, and pass a pointer to that to your function, and hope that the static_cast on each element is valid.

One way, given a std::vector<void*>* foo ;

std::vector<MyStruct*> temp;
for (void* p : *foo){
    temp.push_back(static_cast<MyStruct*>(p));
}

Answer 2

If you don't need to modify the vector<void*> foo then you could just work with the underlying data, by changing your function signature to: void SetDataReferences(MyStruct*const* pVector, const size_t length) (remember that const is left associative, so this is a pointer-to-constant-pointers-to-MyStructs.) This can be called as follows:

SetDataReferences(reinterpret_cast<MyStruct*const*>(data(foo)), size(foo))

If you needed to modify the elements of vector<void*> foo (not the size) you still have the recourse of changing your function signature to: void SetDataReferences(MyStruct** pVector, const size_t length) This can be called as follows:

SetDataReferences(reinterpret_cast<int**>(data(foo)), size(foo))

Live Examples

If you need to modify vector<void*> foo that gets more complicated, you'll need to accept the vector<void*> as your function signature does in the question and cast the elements on use rather than as a group.

Answer 3

I got solution for my problem from this link https://www.codeproject.com/Questions/1261243/How-to-pass-std-vector-void-as-std-vector-mystruct and it is working for me.

If I call SetDataReferences((std::vector<MyStruct*>*)(&p1)) it is working for me without getting any compiler error.