2D Array Pointer (Pointer To 2D Array) in C Programming Language

In this tutorial, we will learn how to use pointers with two-dimensional arrays in the C programming language. A two-dimensional array is an array of arrays, and a pointer to a two-dimensional array is a pointer that points to the first element (the first one-dimensional array) of the 2D array.

Declaring a pointer to a two-dimensional array:

To declare a pointer to a two-dimensional array, specify the data type, followed by an asterisk (*) for the pointer, the name of the pointer, and the dimensions enclosed in square brackets, with the first dimension omitted.

int (*arrayPointer)[4];

In this example, arrayPointer is a pointer to a one-dimensional array of 4 integers. It can be used to point to a two-dimensional array with any number of rows but 4 columns.

Assigning a two-dimensional array to a pointer:

To assign the address of a two-dimensional array to a pointer, use the name of the array (which is a pointer to the first element).

int myArray[3][4];
arrayPointer = myArray;

Accessing elements using a pointer to a two-dimensional array:

To access elements in a two-dimensional array using a pointer, use the pointer name followed by the row and column indices enclosed in square brackets.

int value = arrayPointer[1][2]; // Access the element in the second row and the third column

Example: Iterating over a two-dimensional array using a pointer

Here's an example demonstrating how to iterate over a two-dimensional array using a pointer:

#include <stdio.h>

int main() {
    int myArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    int (*arrayPointer)[4] = myArray;

    // Iterate over the 2D array using a pointer
    for (int row = 0; row < 3; ++row) {
        for (int col = 0; col < 4; ++col) {
            printf("%d ", arrayPointer[row][col]);
        }
        printf("\n");
    }

    return 0;
}

The output will be:

1 2 3 4
5 6 7 8
9 10 11 12

That's it for our tutorial on pointers to two-dimensional arrays in the C programming language. Understanding how to use pointers with 2D arrays is essential when working with dynamic memory allocation or when passing 2D arrays to functions.

Pointer to 2D array in C example:

#include <stdio.h>

int main() {
    int twoDArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    // Pointer to 2D array
    int (*ptr)[4] = twoDArray;

    // Access elements using pointers
    printf("Value at (1,2): %d\n", ptr[1][2]);

    return 0;
}

Declare a pointer to a 2D array and access elements using pointer notation.

How to declare and use 2D array pointers in C:

#include <stdio.h>

int main() {
    int twoDArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    // Declare and initialize a pointer to a 2D array
    int (*ptr)[4] = twoDArray;

    // Access elements using pointers
    printf("Value at (1,2): %d\n", ptr[1][2]);

    return 0;
}

Declare and initialize a pointer to a 2D array and access elements using pointer notation.

Accessing elements with 2D array pointers in C:

#include <stdio.h>

int main() {
    int twoDArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    // Pointer to 2D array
    int (*ptr)[4] = twoDArray;

    // Access elements using pointers
    printf("Value at (1,2): %d\n", ptr[1][2]);

    return 0;
}

Access elements of a 2D array using pointers.

Passing 2D array pointers to functions in C:

#include <stdio.h>

// Function taking a pointer to a 2D array
void printArray(int (*arr)[4]) {
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 4; ++j) {
            printf("%d ", arr[i][j]);
        }
        printf("\n");
    }
}

int main() {
    int twoDArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    // Pass 2D array pointer to function
    printArray(twoDArray);

    return 0;
}

Pass a pointer to a 2D array to a function.

Dynamic allocation of 2D array using pointers in C:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int rows = 3, columns = 4;

    // Dynamic allocation of a 2D array
    int (*dynamicTwoDArray)[columns] = (int (*)[columns])malloc(rows * sizeof(int[columns]));

    // Access and assign values
    dynamicTwoDArray[1][2] = 5;

    // Free memory
    free(dynamicTwoDArray);

    return 0;
}

Dynamically allocate a 2D array using pointers.

Pointer arithmetic with 2D arrays in C:

#include <stdio.h>

int main() {
    int twoDArray[3][4] = {
        {1, 2, 3, 4},
        {5, 6, 7, 8},
        {9, 10, 11, 12}
    };

    // Pointer arithmetic to access elements
    int* ptr = &twoDArray[0][0];
    printf("Value at (1,2): %d\n", *(ptr + 1 * 4 + 2));

    return 0;
}

Use pointer arithmetic to access elements of a 2D array.

C pointer to array of pointers (2D array):

#include <stdio.h>

int main() {
    int row1[] = {1, 2, 3, 4};
    int row2[] = {5, 6, 7, 8};
    int row3[] = {9, 10, 11, 12};

    // Pointer to an array of pointers
    int* ptrArray[] = {row1, row2, row3};

    // Access elements using pointers
    printf("Value at (1,2): %d\n", ptrArray[1][2]);

    return 0;
}

Declare a pointer to an array of pointers representing a 2D array.