Multidimensional Arrays in C: 2D and 3D Arrays

Multidimensional Arrays in C: An Overview

Multidimensional Arrays in C

Syntax

dataType arrayName[size1][size2]...[sizeN];

Example

int arr[5][4]; 

Here, an integer type 2D array, “arr” is declared with 5 rows and 4 columns thus a total of 20 integer elements.

In the same manner, as above, a 3D array can be declared.

Example

int arr[2][4][3];

The array arr can store 24 integer elements.

How to initialize a multidimensional array in C?

2D array

int arr[2][3] = {{1, 3, 0}, {-1, 5, 9}};
 
int arr[][3] = {{1, 3, 0}, {-1, 5, 9}};
 
int arr[2][3] = {1, 3, 0, -1, 5, 9};

3D array

int arr[2][3][4] = {
 {{3, 4, 2, 3}, {0, -3, 9, 11}, {23, 12, 23, 2}},
 {{13, 4, 56, 3}, {5, 9, 3, 5}, {3, 1, 4, 9}}
 };

Read More - Top 50 Mostly Asked C Interview Questions

How to access the elements of a multi-dimensional array in C?

2D array

Example

#include <stdio.h>
int main() {
 int arr[2][3] = { {5, 6, 7}, {3, 6, 8} };
 printf("%d", arr[0][2]);
 return 0;
}

The printf statement in the above code accesses the value of the element in the first row (0) and third column (2) of the array, “arr”.

Output

7

3D array

Example

#include <stdio.h>
int main() {
 int arr[2][3][4] = {
 {{3, 4, 2, 3}, {0, -3, 9, 11}, {23, 12, 23, 2}},
 {{13, 4, 56, 3}, {5, 9, 3, 5}, {3, 1, 4, 9}}
 };
 printf("%d", arr[0][2][3]);

 return 0;
}

The printf statement in the above code in the C Online Compiler accesses the value of the element in the first row (0), the third column (2), and fourth dimension (3) of the array, “arr”.

Output

2

How to change the elements of a multidimensional array in C?

To change the value of a specific element, refer to the index number in each dimension in the C Editor.

2D array

Example

#include <stdio.h>
int main() {
 int matrix[2][3] = { {5, 6, 7}, {3, 6, 8} };
 matrix[0][2] = 9;
 printf("%d", matrix[0][2]); // Now outputs 9 instead of 1
 return 0;
}

Output

9

3D array

Example

#include <stdio.h>
int main() {
 // Define a 3D array
 int array3D[2][3][4];

 // Initialize the 3D array
 int value = 1;
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 3; j++) {
 for (int k = 0; k < 4; k++) {
 array3D[i][j][k] = value++;
 }
 }
 }

 // Display the original 3D array
 printf("Original 3D Array:\n");
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 3; j++) {
 for (int k = 0; k < 4; k++) {
 printf("%3d ", array3D[i][j][k]);
 }
 printf("\n");
 }
 printf("\n");
 }

 // Change elements in the 3D array
 array3D[0][1][2] = 100;
 array3D[1][0][3] = 200;

 // Display the modified 3D array
 printf("\nModified 3D Array:\n");
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 3; j++) {
 for (int k = 0; k < 4; k++) {
 printf("%3d ", array3D[i][j][k]);
 }
 printf("\n");
 }
 printf("\n");
 }

 return 0;
}
 

Output

Original 3D Array:
 1 2 3 4 
 5 6 7 8 
 9 10 11 12 

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

Modified 3D Array:
 1 2 3 4 
 5 6 100 8 
 9 10 11 12 

 13 14 15 200 
 17 18 19 20 
 21 22 23 24 

How to traverse a multidimensional array in C?

To loop through a multi-dimensional array, you need one for loop for each of the array's dimensions.

2D array

Example

#include <stdio.h>
int main() {
 int arr[2][3] = { {5, 6, 7}, {3, 6, 8} };
 int i, j;

 for (i = 0; i < 2; i++) {
 for (j = 0; j < 3; j++) {
 printf("%d\n", arr[i][j]);
 }
 }

 return 0;
}

Output

5
6
7
3
6
8

3D array

Example

#include <stdio.h>

int main() {
 // Define a 3D array
 int array3D[2][3][4];

 // Initialize the 3D array
 int value = 1;
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 3; j++) {
 for (int k = 0; k < 4; k++) {
 array3D[i][j][k] = value++;
 }
 }
 }

 // Traverse and display the 3D array
 printf("Traversing 3D Array:\n");
 for (int i = 0; i < 2; i++) {
 for (int j = 0; j < 3; j++) {
 for (int k = 0; k < 4; k++) {
 printf("array3D[%d][%d][%d] = %d\n", i, j, k, array3D[i][j][k]);
 }
 }
 }

 return 0;
}

Output

Traversing 3D Array:
array3D[0][0][0] = 1
array3D[0][0][1] = 2
array3D[0][0][2] = 3
array3D[0][0][3] = 4
array3D[0][1][0] = 5
array3D[0][1][1] = 6
array3D[0][1][2] = 7
array3D[0][1][3] = 8
array3D[0][2][0] = 9
array3D[0][2][1] = 10
array3D[0][2][2] = 11
array3D[0][2][3] = 12
array3D[1][0][0] = 13
array3D[1][0][1] = 14
array3D[1][0][2] = 15
array3D[1][0][3] = 16
array3D[1][1][0] = 17
array3D[1][1][1] = 18
array3D[1][1][2] = 19
array3D[1][1][3] = 20
array3D[1][2][0] = 21
array3D[1][2][1] = 22
array3D[1][2][2] = 23
array3D[1][2][3] = 24

Input and Output Multidimensional Array Elements in C

We can use the scanf() function to take inputs of an array from the user.

2D array

Example

#include <stdio.h>

int main() {
 int marks[2][3];

 // Prompt user to enter grades
 for (int i = 0; i < 2; i++)
 {
 printf("Enter the marks for student %d:\n", i + 1);
 for (int j = 0; j < 3; j++)
 {
 printf("Subject %d: ", j + 1);
 scanf("%d", &marks[i][j]);
 }
 }
 printf("The marks entered are:\n");

 // Display entered grades
 for (int i = 0; i < 2; i++)
 {
 printf("Student %d: ", i + 1);
 for (int j = 0; j < 3; j++)
 {
 printf("Subject %d: %d\n", j + 1, marks[i][j]);
 }
 }

 return 0;
}

The above program in the C Playground is to print the marks of two students in 3 subjects. The first for loop indicates the student number. The 2nd for loop is used to take the marks of the 3 subjects for the student in the first for loop from the user. In the same way, the two for loops work for printing the output

Output

Enter the marks for student 1:
Subject 1: 85
Subject 2: 92
Subject 3: 78
Enter the marks for student 2:
Subject 1: 75
Subject 2: 88
Subject 3: 91
The marks entered are:
Student 1: Subject 1: 85
Student 1: Subject 2: 92
Student 1: Subject 3: 78
Student 2: Subject 1: 75
Student 2: Subject 2: 88
Student 2: Subject 3: 91

3D array

Example

/* C Program to dempnstarte a 3D array whose values are taken from the user */

#include <stdio.h>
int main()
{
 int arr[2][3][2];

 printf("Enter the values as given by the user: \n");

 for (int i = 0; i < 2; ++i)
 {
 for (int j = 0; j < 3; ++j)
 {
 for (int k = 0; k < 2; ++k)
 {
 scanf("%d", &arr[i][j][k]);
 }
 }
 }

 // Printing values with the proper index.

 printf("\nDisplaying values:\n");
 for (int i = 0; i < 2; ++i)
 {
 for (int j = 0; j < 3; ++j)
 {
 for (int k = 0; k < 2; ++k)
 {
 printf("arr[%d][%d][%d] = %d\n", i, j, k, arr[i][j][k]);
 }
 }
 }
 return 0;
}

Output

Enter the values as given by the user:
1
2
3
4
5
6
7
8
9
10
11
12

Displaying values:
arr[0][0][0] = 1
arr[0][0][1] = 2
arr[0][1][0] = 3
arr[0][1][1] = 4
arr[0][2][0] = 5
arr[0][2][1] = 6
arr[1][0][0] = 7
arr[1][0][1] = 8
arr[1][1][0] = 9
arr[1][1][1] = 10
arr[1][2][0] = 11
arr[1][2][1] = 12

Summary