Types of Arrays
Arrays are categorized based on the number of indices used to access elements.
A. One-Dimensional Array (1D)
A One-Dimensional Array (or 1D Array) is the simplest form of an array. It is a linear list of elements of the same type, stored in contiguous memory locations. You can imagine it as a single row of lockers, where each locker has a unique index number. 
JavaPythonCC++
public class OneDimensionalArray {
public static void main(String[] args) {
// 1. Static Initialization (Declaration + Creation + Assignment)
// Used when we already know the data
int[] marks = {85, 90, 78, 92, 88};
System.out.println("First student's mark: " + marks[0]); // Accessing index 0
// 2. Dynamic Initialization (Declaration + Memory Allocation)
// Used when we don't know the values yet
String[] fruits = new String[4]; // Creates an empty array of size 4
// Assigning values manually
fruits[0] = "Apple";
fruits[1] = "Banana";
fruits[2] = "Mango";
fruits[3] = "Orange";
System.out.println("\nList of Fruits:");
// Traversal using a for-loop
for (int i = 0; i < fruits.length; i++) {
System.out.println("Index " + i + ": " + fruits[i]);
}
// Traversal using Enhanced For-Loop (For-Each)
System.out.println("\nMarks:");
for (int m : marks) {
System.out.print(m + " ");
}
}
}
# One Dimensional Array Example
# 1. Static Initialization
# Used when we already know the data
marks = [85, 90, 78, 92, 88]
print("First student's mark:", marks[0]) # Accessing index 0
# 2. Dynamic Initialization
# Used when we don't know the values yet
fruits = [None] * 4 # Creates an empty list of size 4
# Assigning values manually
fruits[0] = "Apple"
fruits[1] = "Banana"
fruits[2] = "Mango"
fruits[3] = "Orange"
print("\nList of Fruits:")
# Traversal using a for-loop
for i in range(len(fruits)):
print("Index", i, ":", fruits[i])
# Traversal using For-Each style loop
print("\nMarks:")
for m in marks:
print(m, end=" ")
#include <stdio.h>
int main() {
// 1. Static Initialization (Declaration + Creation + Assignment)
int marks[] = {85, 90, 78, 92, 88};
printf("First student's mark: %d\n", marks[0]);
// 2. Dynamic Initialization (Declaration + Memory Allocation)
char *fruits[4];
// Assigning values manually
fruits[0] = "Apple";
fruits[1] = "Banana";
fruits[2] = "Mango";
fruits[3] = "Orange";
printf("\nList of Fruits:\n");
// Traversal using a for-loop
for (int i = 0; i < 4; i++) {
printf("Index %d: %s\n", i, fruits[i]);
}
printf("\nMarks:\n");
for (int i = 0; i < 5; i++) {
printf("%d ", marks[i]);
}
return 0;
}
#include <iostream>
using namespace std;
int main() {
// 1. Static Initialization (Declaration + Creation + Assignment)
int marks[] = {85, 90, 78, 92, 88};
cout << "First student's mark: " << marks[0] << endl;
// 2. Dynamic Initialization (Declaration + Memory Allocation)
string fruits[4];
// Assigning values manually
fruits[0] = "Apple";
fruits[1] = "Banana";
fruits[2] = "Mango";
fruits[3] = "Orange";
cout << "\nList of Fruits:" << endl;
// Traversal using a for-loop
for (int i = 0; i < 4; i++) {
cout << "Index " << i << ": " << fruits[i] << endl;
}
// Traversal similar to For-Each
cout << "\nMarks:" << endl;
for (int m : marks) {
cout << m << " ";
}
return 0;
}
- Analogy: A row of lockers in a school hallway.
- Use Case: Storing a list of student marks or daily temperatures.
B. Multi-Dimensional Array (2D, 3D)
Arrays within arrays. The most common is the 2D Array (Matrix).
JavaPythonCC++
public class TwoDimensionalArray {
public static void main(String[] args) {
// Declaration: int[rows][columns]
// Example: A 3x3 Matrix
int[][] matrix = {
{1, 2, 3}, // Row 0
{4, 5, 6}, // Row 1
{7, 8, 9} // Row 2
};
System.out.println("Element at Row 1, Column 2 (Index 1,2): " + matrix[1][2]); // Output: 6
System.out.println("\nDisplaying the 3x3 Matrix:");
// Outer loop for Rows
for (int i = 0; i < matrix.length; i++) {
// Inner loop for Columns
for (int j = 0; j < matrix[i].length; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println(); // New line after every row
}
}
}
# Two Dimensional Array Example
# Example: A 3x3 Matrix
matrix = [
[1, 2, 3], # Row 0
[4, 5, 6], # Row 1
[7, 8, 9] # Row 2
]
print("Element at Row 1, Column 2 (Index 1,2):", matrix[1][2]) # Output: 6
print("\nDisplaying the 3x3 Matrix:")
# Outer loop for Rows
for i in range(len(matrix)):
# Inner loop for Columns
for j in range(len(matrix[i])):
print(matrix[i][j], end=" ")
print() # New line after every row
#include <stdio.h>
int main() {
// Declaration of a 3x3 Matrix
int matrix[3][3] = {
{1, 2, 3}, // Row 0
{4, 5, 6}, // Row 1
{7, 8, 9} // Row 2
};
printf("Element at Row 1, Column 2 (Index 1,2): %d\n", matrix[1][2]);
printf("\nDisplaying the 3x3 Matrix:\n");
// Outer loop for Rows
for (int i = 0; i < 3; i++) {
// Inner loop for Columns
for (int j = 0; j < 3; j++) {
printf("%d ", matrix[i][j]);
}
printf("\n"); // New line after every row
}
return 0;
}
#include <iostream>
using namespace std;
int main() {
// Declaration of a 3x3 Matrix
int matrix[3][3] = {
{1, 2, 3}, // Row 0
{4, 5, 6}, // Row 1
{7, 8, 9} // Row 2
};
cout << "Element at Row 1, Column 2 (Index 1,2): " << matrix[1][2] << endl;
cout << "\nDisplaying the 3x3 Matrix:" << endl;
// Outer loop for Rows
for (int i = 0; i < 3; i++) {
// Inner loop for Columns
for (int j = 0; j < 3; j++) {
cout << matrix[i][j] << " ";
}
cout << endl; // New line after every row
}
return 0;
}
- Analogy: A spreadsheet or a chessboard (Rows and Columns).
- Use Case: Storing an image (pixels), matrices, or tables.