Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://www.geeksforgeeks.org/c/how-to-initialize-a-3d-array-in-c/ below:

How to Initialize a 3D Array in C?

Last Updated : 26 Jul, 2025

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.

There are three ways in which a 3D array can be initialized in C:

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

int arr[2][3][2] = { { {0, 1}, {2, 3}, {4, 5} },
{ {6, 7}, {8, 9}, {10, 11} }};

Here, the braces will help in navigating into the layers of the 3D array. The outermost set of braces groups all the elements of the 3D array. The second set of braces defines the specific 2D array (or depth level) starting from index 0. The innermost set of braces holds the values for each row within that 2D array, assigning values from row 0 to the last row.

We can also skip the inner braces and initialize the arrays as:

int arr[2][3][2] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};

// C Program to illustrate how to initialize 3D array
// using initializer list
#include <stdio.h>

int main() {
  
    // Directly initializing 3D array at the time of
    // declaration
    int arr[2][3][2] = { { {0, 1}, {2, 3}, {4, 5} },
                       { {6, 7}, {8, 9}, {10, 11} }};
  	
  	// Printing the array
  	for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < 2; k++) {
                printf("%d ", arr[i][j][k]);
            }
            printf("\n");
        }
        printf("\n");
    }


    return 0;
}

0 1 
2 3 
4 5 

6 7 
8 9 
10 11 

Time Complexity: O(d * m * n), where d is the number of 2D arrays (or depth), m and n are the number of rows and columns in each 2D array.
Auxiliary Space: O(1)

C language also provides a feature to initialize all the elements of the 3D array to 0. This feature is limited to the numeric arrays or other type that can be converted to numeric values.

int arr[2][3][2] = { 0 }

// C Program to illustrate how to initialize
// a 3D array with zero
#include <stdio.h>

int main() {
  
    // Initializing a 2x3x2 3D array
    int arr[2][3][2] = {0};

    // Printing the 3D array
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < 2; k++) {
                printf("%d ", arr[i][j][k]);
            }
            printf("\n");
        }
        printf("\n");
    }

    return 0;
}

0 0 
0 0 
0 0 

0 0 
0 0 
0 0 

Time Complexity: O(d * m * n), where d is the number of 2D arrays (or depth), m and n are the number of rows and columns in each 2D array.
Auxiliary Space: O(1)

In above methods of initialization, the values should be known before the compilation of the program. But we can also initialize the 3D array at runtime using loops. We use three nested loops to go to each element of the array and initialize it to some value. This value is generally taken as input from some source such as file or generated from some series or copied from other arrays.

// C Program to illustrate how to initialize
// a 3D array using loops
#include <stdio.h>

int main() {
  
    // Defining a 2x3x2 3D array
    int arr[2][3][2];

    // Variable to assign values to array elements
    int count = 1;

    // Initializing the array using loops
    for (int i = 0; i < 2; i++)
        for (int j = 0; j < 3; j++)
            for (int k = 0; k < 2; k++)
                arr[i][j][k] = count++;

    // Printing the 3D array
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < 2; k++) {
                printf("%d ", arr[i][j][k]);
            }
            printf("\n");
        }
        printf("\n");
    }

    return 0;
}

1 2 
3 4 
5 6 

7 8 
9 10 
11 12 

Time Complexity: O(d * m * n), where d is the number of 2D arrays (or depth), m and n are the number of rows and columns in each 2D array.
Auxiliary Space: O(1)

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4