Pointer to Pointer Dynamic Allocation
A pointer to pointer, denoted as double pointer (**).
This is a pointer that holds the memory address of another pointer. In simple words, it is a variable whose value is the address of another pointer. This concept might sound complex at first, but it provides a powerful mechanism for dealing with advanced dynamic memory allocation.
Syntax
main.cpp
12345678910111213#include <iostream> int main() { int x = 10; int *ptr1 = &x; int **ptr2 = &ptr1; // Accessing values using double pointer std::cout << "Address stored in ptr2 (address of ptr1): " << ptr2 << std::endl; std::cout << "Address stored in ptr1 (address of x): " << *ptr2 << std::endl; std::cout << "Value of x: " << **ptr2 << std::endl; }
- ptr1: is a pointer to an integer (
int*); - ptr2: is a double pointer to an integer (
int**).
Dynamic Allocation of a Two-Dimensional Array
If you want to create a two-dimensional array dynamically (at runtime) you have to use a pointer to a pointer for the rows.
And then initialize each row with dynamic array (like in previous chapter)
Swipe to start coding
Imagine you are working with a spreadsheet application where you need to create a table of numbers dynamically.
In this task, you will work with dynamic two-dimensional arrays and practice both allocation and deallocation of memory.
- Inside the function
createAndPrint2DArray, dynamically allocate a 2D array of integers with the given number of rows and columns. - Fill the array with values calculated as
row * columns + column, so each element is unique and depends on its position. - Print the array to the console in a tabular format.
- Properly release all dynamically allocated memory using
delete[]for each row and then for the array of pointers itself.
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Can you explain how to declare and use a double pointer in code?
What are some practical examples where double pointers are useful?
Can you show how to dynamically allocate a 2D array using double pointers?
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A pointer to pointer, denoted as double pointer (**).
This is a pointer that holds the memory address of another pointer. In simple words, it is a variable whose value is the address of another pointer. This concept might sound complex at first, but it provides a powerful mechanism for dealing with advanced dynamic memory allocation.
Syntax
main.cpp
12345678910111213#include <iostream> int main() { int x = 10; int *ptr1 = &x; int **ptr2 = &ptr1; // Accessing values using double pointer std::cout << "Address stored in ptr2 (address of ptr1): " << ptr2 << std::endl; std::cout << "Address stored in ptr1 (address of x): " << *ptr2 << std::endl; std::cout << "Value of x: " << **ptr2 << std::endl; }
- ptr1: is a pointer to an integer (
int*); - ptr2: is a double pointer to an integer (
int**).
Dynamic Allocation of a Two-Dimensional Array
If you want to create a two-dimensional array dynamically (at runtime) you have to use a pointer to a pointer for the rows.
And then initialize each row with dynamic array (like in previous chapter)
Swipe to start coding
Imagine you are working with a spreadsheet application where you need to create a table of numbers dynamically.
In this task, you will work with dynamic two-dimensional arrays and practice both allocation and deallocation of memory.
- Inside the function
createAndPrint2DArray, dynamically allocate a 2D array of integers with the given number of rows and columns. - Fill the array with values calculated as
row * columns + column, so each element is unique and depends on its position. - Print the array to the console in a tabular format.
- Properly release all dynamically allocated memory using
delete[]for each row and then for the array of pointers itself.
Løsning
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