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

#include <iostream>

int main()

{

int x = 10;

int *ptr1 = &x;

int **ptr2 = &ptr1;

// Accessing values using double pointer

std::cout << "Location of ptr2: " << ptr2 << std::endl;

std::cout << "Location of ptr1: " << *ptr2 << std::endl;

std::cout << "Value of x: " << **ptr2 << std::endl;

}


              12345678910111213
            
#include <iostream>

int main()
{
    int x = 10;
    int *ptr1 = &x;
    int **ptr2 = &ptr1;

    // Accessing values using double pointer
    std::cout << "Location of ptr2: " << ptr2 << std::endl;
    std::cout << "Location of ptr1: " << *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)

Tarea

Swipe to start coding

Dynamically allocate a two dimensional array.
Dynamically allocate the arrays as elements.
Free all allocated memory.

Solución

solution

#include <iostream>

int main()

{

int rows = 3, columns = 5;

int **twoDArray = new int*[rows];

for (int row = 0; row < rows; row++)

twoDArray[row] = new int[columns];

for (int row = 0; row < rows; row++)

for (int column = 0; column < columns; column++)

{

twoDArray[row][column] = row * columns + column;

std::cout << twoDArray[row][column] << ' ';

}

for (int row = 0; row < rows; row++)

delete[] twoDArray[row];

delete[] twoDArray;

}

¿Todo estuvo claro?

¡Gracias por tus comentarios!

Sección 4. Capítulo 4

#include <iostream>

int main()

{

int rows = 3, columns = 5;

int __twoDArray = ___ int_[rows];

for (int row = 0; row < rows; row++)

twoDArray[row] = ___ int[columns];

// Initialization of the array with some values

for (int row = 0; row < rows; row++)

for (int column = 0; column < columns; column++)

{

twoDArray[row][column] = row * columns + column;

std::cout << twoDArray[row][column] << ' ';

}

for (int row = 0; row < rows; row++)

___[] twoDArray[_];

___[] twoDArray;

}

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