How to Initialize a 3D Array in C?

In C, a 3D array is a type of multidimensional array that stores data in a three-dimensional grid. It has three dimensions, allowing it to store data in three directions: rows, columns, and depth. In this article, we will learn how to initialize a 3D array in C.

Initializing Three Dimensional Array in C

We can initialize a 3D array at the time of declaration by providing the values in curly braces {} using the following syntax:

Syntax to Initialize 3D Array in C

dataType arrayName[depth][row size][column size] = {
    {
        {depth0row0col0, depth0row0col1, ...},
        {depth0row1col0, depth0row1col1, ...},
        ...
};

For runtime initialization, we need to use nested loops to assign values.

C Program to Initialize a 3D Array

The below program demonstrates the initialization of a 3D array in C.

C

// C Program to illustrate how to initialize 3D array

#include <stdio.h>

// function to print the array
void print3DArray(int depth, int rows, int cols,
                  int arr[][3][4])
{
    for (int i = 0; i < depth; i++) {
        printf("Depth %d:\n", i + 1);
        for (int j = 0; j < rows; j++) {
            for (int k = 0; k < cols; k++) {
                printf("%d ", arr[i][j][k]);
            }
            printf("\n");
        }
        printf("\n");
    }
}

int main()
{
    // directly initializing 3D array at the time of
    // declaration
    int arr1[2][3][4] = { { { 1, 2, 3, 4 },
                            { 5, 6, 7, 8 },
                            { 9, 10, 11, 12 } },
                          { { 13, 14, 15, 16 },
                            { 17, 18, 19, 20 },
                            { 21, 22, 23, 24 } } };

    // printing array 1
    printf("Printing arr1 \n");
    print3DArray(2, 3, 4, arr1);
    printf("\n");

    // runtime initialization
    int arr2[2][3][4];
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            for (int k = 0; k < 2; k++) {
                arr2[i][j][k] = 0;
            }
        }
    }

    // printing array 2
    printf("Printing arr2 \n");
    print3DArray(2, 3, 4, arr2);

    return 0;
}

Output

Printing arr1
Depth 1:
1 2 3 4 
5 6 7 8 
9 10 11 12 

Depth 2:
13 14 15 16 
17 18 19 20 
21 22 23 24 


Printing arr2 
Depth 1:
0 0 0 0 
0 0 0 0 
0 0 0 0 

Depth 2:
0 0 0 0 
0 0 0 0 
0 0 0 0 

Time Complexity: O(N), where N is the total number of elements.
Space Complexity: O(1)