Pointer to a std::vector object(s)

Question

I need to do the following:

 std::vector<std::string> A; 
 std::vector<std::string> B;
 
 ==> pointer_to_vector<std::string> ptr;

//Some Code
ptr = A; //ptr points to object A

//Some More Code
ptr = B; // //ptr points to object B

During the program, ptr needs to refer to both A and B at different times. How would it be implemented and considering that std::vector makes reallocations, how to use smart pointers here?

"how to use smart pointers here?" why do you need a smart pointer here? — Slava, Nov 04 '20 at 22:09
There is no need for a smart pointer here, a plain raw pointer will suffice. — Remy Lebeau, Nov 04 '20 at 22:44
Smart pointers manage [ownership](https://stackoverflow.com/questions/49024982/what-is-ownership-of-resources-or-pointers). In the case of an Automatic variable, ownership is already managed. When the variable goes out of scope, it's taken care of. — user4581301, Nov 04 '20 at 23:08

score 1 · Accepted Answer · answered Nov 04 '20 at 22:30

You define a pointer to a vector the same way you define a pointer to any other type - using * in the pointer declaration, and the & address-of operator to get the memory address of a variable to assign to the pointer, eg:

std::vector<std::string> A; 
std::vector<std::string> B;
 
std::vector<std::string> *ptr;

//Some Code
ptr = &A; //ptr points to object A

//Some More Code
ptr = &B; // //ptr points to object B

Or, use std::addressof(), if any objects overload operator& for their own purposes (which std::vector does not), eg:

//Some Code
ptr = std::addressof(A); //ptr points to object A

//Some More Code
ptr = std::addressof(B); // //ptr points to object B

Pointer to a std::vector object(s)

1 Answers1