4 Dimensional Array in C/C++

A 4 dimensional array in C is an array of 3 dimensional arrays, where each 3D array contains multiple 2D arrays, and each 2D array contains multiple 1D arrays. This creates a hierarchical structure with four levels of indexing.

Syntax

datatype array_name[dimension1][dimension2][dimension3][dimension4];

For example:

int arr[3][2][3][4];  /* 3 blocks, 2 tables, 3 rows, 4 columns */

Declaration and Initialization

You can initialize a 4D array during declaration using nested braces −

#include <stdio.h>

int main() {
    int arr[2][2][2][3] = {
        {
            { {1, 2, 3}, {4, 5, 6} },
            { {7, 8, 9}, {0, 1, 2} }
        },
        {
            { {10, 11, 12}, {13, 14, 15} },
            { {16, 17, 18}, {19, 20, 21} }
        }
    };

    printf("Element at arr[0][1][0][2]: %d\n", arr[0][1][0][2]);
    printf("Element at arr[1][0][1][1]: %d\n", arr[1][0][1][1]);
    
    return 0;
}

Element at arr[0][1][0][2]: 9
Element at arr[1][0][1][1]: 14

Traversing a 4D Array

To access all elements, you need four nested loops −

#include <stdio.h>

int main() {
    int arr[2][2][2][3] = {
        {
            { {1, 2, 3}, {4, 5, 6} },
            { {7, 8, 9}, {10, 11, 12} }
        },
        {
            { {13, 14, 15}, {16, 17, 18} },
            { {19, 20, 21}, {22, 23, 24} }
        }
    };

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

Block 0:
  Table 0:
    Row 0: 1 2 3 
    Row 1: 4 5 6 
  Table 1:
    Row 0: 7 8 9 
    Row 1: 10 11 12 
Block 1:
  Table 0:
    Row 0: 13 14 15 
    Row 1: 16 17 18 
  Table 1:
    Row 0: 19 20 21 
    Row 1: 22 23 24 

Memory Size Calculation

The memory size of a 4D array is calculated as: dimension1 × dimension2 × dimension3 × dimension4 × sizeof(datatype)

#include <stdio.h>

int main() {
    int arr[3][2][3][4];
    
    int total_elements = 3 * 2 * 3 * 4;
    int memory_size = sizeof(arr);
    
    printf("Total elements: %d\n", total_elements);
    printf("Memory size: %d bytes\n", memory_size);
    printf("Size per element: %lu bytes\n", sizeof(int));
    
    return 0;
}

Total elements: 72
Memory size: 288 bytes
Size per element: 4 bytes

Key Points

• 4D arrays require four indices: arr[block][table][row][column]
• Memory is allocated contiguously in row-major order
• Use four nested loops to traverse all elements
• Total memory = product of all dimensions × sizeof(datatype)

Conclusion

4D arrays in C provide a way to organize data in four dimensions, useful for complex data structures like time-series matrices or multi-dimensional grids. They follow the same principles as lower-dimensional arrays but require careful indexing and initialization.