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Create Vector of Pointers in C++

Create Vector of Pointers in C++

Created: December-06, 2020 | Updated: December-10, 2020

Use [] Notation to Create Vector of Pointers in C++
Use the new Operator to Create Vector of Pointers on Dynamic Memory in C++
Use the std::vector Container to Create Vector of Pointers in C++

This article will explain several methods of how to create a vector of pointers in C++.

Use `[]` Notation to Create Vector of Pointers in C++

Since the pointer types can be modified easily, we will use int * in the following examples to declare a vector of pointers. Alternatively, we can use the void * pointer if you require a generic address type to store opaque data structures or, on the contrary, use a pointer to a custom defined class.

This solution uses a C-style array notation - [] that declares a fixed-length array. It is similar to the regular array declaration, but in this case, we are interested in accessing each element's addresses. We are using the & (address of) operator to access pointers in the vector and print them out to the console. Note that these memory addresses are located on the stack memory.

              #include <iostream> #include <vector>  using std::cout; using std::vector; using std::endl;  constexpr int WIDTH = 8;  int main() {     int *pointers_vec[WIDTH];      cout << "pointers_vec addresses:" << endl;     for(auto &i : pointers_vec) {         cout << &i << endl;     }     cout << endl;      return EXIT_SUCCESS; }

Output:

              pointers_vec addresses: 0x7ffecd7a00d0 0x7ffecd7a00d8 0x7ffecd7a00e0 0x7ffecd7a00e8 0x7ffecd7a00f0 0x7ffecd7a00f8 0x7ffecd7a0100 0x7ffecd7a0108

Use the `new` Operator to Create Vector of Pointers on Dynamic Memory in C++

On the other hand, we can utilize the new operator to create a vector of pointers dynamically allocated on the heap.

This solution requires the programmer to free up the memory before the program exits; otherwise, the code will suffer from the memory leak, which can be a massive problem in long-running applications and resource-constrained hardware environments. Note that we use the delete [] notation to clean up each location in a dynamically allocated vector.

              #include <iostream> #include <vector>  using std::cout; using std::vector; using std::endl;  constexpr int WIDTH = 8;  int main() {     int *vector_of_pointers = new int[WIDTH];      cout << "vector_of_pointers addresses:" << endl;     for(int i = 0; i < WIDTH; ++i) {         cout << &vector_of_pointers[i] << endl;     }     cout << endl;      delete [] vector_of_pointers;     return EXIT_SUCCESS; }

Output:

              vector_of_pointers addresses: 0x2561c20 0x2561c28 0x2561c30 0x2561c38 0x2561c40 0x2561c48 0x2561c50 0x2561c58

Use the `std::vector` Container to Create Vector of Pointers in C++

std::vector offers rich functionality to allocate a vector of pointers and manipulate the vector with multiple built-in functions. This method provides a more flexible interface for new element creation during the run-time. Notice that we initialized the vector elements with the nullptr value, as shown in the following example.

              #include <iostream> #include <vector>  using std::cout; using std::vector; using std::endl;  constexpr int WIDTH = 8;  int main() {     vector<int *> vector_p(WIDTH, nullptr);      cout << "vector_p addresses:" << endl;     for(int i = 0; i < WIDTH; ++i) {         cout << &vector_p[i] << endl;     }     cout << endl;      return EXIT_SUCCESS; }

Output:

              vector_p addresses: 0x1255c20 0x1255c28 0x1255c30 0x1255c38 0x1255c40 0x1255c48 0x1255c50 0x1255c58

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