Lære 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


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#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)

Opgave

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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Sektion 4. Kapitel 4

single

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Suggested prompts:

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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