pointer to pointer to constant

Question

I have a function const void* getData() which returns a pointer to constant data const void* I need to write a wrapper to this function that gets an (output) argument in which it should return the above pointer.

void wrapGetData([type] ppData) {
*ppData = getData();
}

What should be the [type] ? void ** is not sutable,since getData() returns pointer to the const

Answer 1

If getData() returns void const * , then [type] should be void const * & :

void wrapGetData(void const * & ppData) 
{
    ppData = getData();
}

Note that & is needed, as ppData is output parameter.

You can call this function as:

void const * output;

wrapGetData(output); 

This is a bit different from the other solution in which you have to call the function as:

wrapGetData(&output); //if [type] = const void **

Note that const void* and void const* are same thing. So don't confuse with the syntax.

---

This is a bit different from the other solution in which you have to call the function as:

wrapGetData(&output); //if [type] = const void **

Hope that helps.

Answer 2

const void** :

const void *getData() {
  return nullptr;
}

void wrapGetData(const void** ppData) {
  *ppData = getData();
}

int main() {
  const void *p;
  wrapGetData(&p);
}