Arrays

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Definition of Arrays

An array is a collection of elements (like numbers or strings) stored under one variable name.

• Single-dimensional arrays store data in a simple list format.
• Multi-dimensional arrays store data in table or grid format (like rows and columns).

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C++

Syntax:

// Single-dimensional
int nums[3];               // Empty array of size 3
int nums2[] = {1, 2, 3};   // Pre-filled

// Multi-dimensional
int grid[2][3];            // 2 rows, 3 columns
int matrix[2][2] = { {1, 2}, {3, 4} };

Example

#include <iostream>

int main() {
    // Single-dimensional array
    int scores[] = { 90, 80, 70 };
    std::cout << scores[0] << std::endl; // Output: 90

    // Multi-dimensional array
    int matrix[2][2] = { {1, 2}, {3, 4} };
    std::cout << matrix[1][0] << std::endl; // Output: 3 (2nd row, 1st column)

    return 0;
}

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C#

Syntax:

// Single-dimensional
int[] nums = new int[3]; // Empty array of size 3
int[] nums2 = {1, 2, 3}; // Pre-filled

// Multi-dimensional
int[,] grid = new int[2, 3]; // 2 rows, 3 columns
int[,] matrix = { {1, 2}, {3, 4} };

Example

// Single-dimensional array
int[] scores = { 90, 80, 70 };
Console.WriteLine(scores[0]); // Output: 90

// Multi-dimensional array
int[,] matrix = { {1, 2}, {3, 4} };
Console.WriteLine(matrix[1, 0]); // Output: 3 (2nd row, 1st column)

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Java

Syntax:

// Single-dimensional
int[] nums = new int[3];
int[] nums2 = {1, 2, 3};

// Multi-dimensional
int[][] matrix = new int[2][3]; // 2 rows, 3 columns
int[][] matrix2 = { {1, 2}, {3, 4} };

Example

// Single-dimensional
int[] scores = { 90, 80, 70 };
System.out.println(scores[0]); // Output: 90

// Multi-dimensional
int[][] matrix = {
    {1, 2},
    {3, 4}
};
System.out.println(matrix[1][0]); // Output: 3

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Python

Syntax:

# Single-dimensional
arr = [1, 2, 3]

# Multi-dimensional (list of lists)
matrix = [
    [1, 2],
    [3, 4]
]

Example

# Single-dimensional array (list)
scores = [90, 80, 70]
print(scores[0])  # Output: 90

# Multi-dimensional array (2D list)
matrix = [[1, 2], [3, 4]]
print(matrix[1][0])  # Output: 3 (2nd row, 1st element)

For real numerical multi-dimensional arrays, use NumPy: import numpy as np

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JavaScript

Syntax:

// Single-dimensional
let nums = [1, 2, 3];

// Multi-dimensional (array of arrays)
let matrix = [
    [1, 2],
    [3, 4]
];

Example

// Single-dimensional
let scores = [90, 80, 70];
console.log(scores[0]); // Output: 90

// Multi-dimensional
let matrix = [[1, 2], [3, 4]];
console.log(matrix[1][0]); // Output: 3

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TypeScript

Syntax

// Single-dimensional array
let arr: number[] = [value1, value2, value3];

// Multi-dimensional array (array of arrays)
let arr: number[][] = [
  [row1col1, row1col2],
  [row2col1, row2col2]
];

// Accessing elements
arr[index]              // Single-dimensional
arr[rowIndex][colIndex] // Multi-dimensional

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Example

// Single-dimensional array
let scores: number[] = [90, 80, 70];
console.log(scores[0]); // Output: 90

// Multi-dimensional array
let matrix: number[][] = [
  [1, 2],
  [3, 4]
];
console.log(matrix[1][0]); // Output: 3 (2nd row, 1st column)

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Array Feature Summary Table

Feature	C++	C#	Java	Python	JavaScript	TypeScript
Single-dimensional array	int arr[] = {1, 2, 3};	int[] arr = {1,2,3}	int[] arr = {1,2,3}	arr = [1,2,3]	let arr = [1,2,3]	let arr: number[] = [1,2,3]
Multi-dimensional array	int arr[2][2] = {{1,2},{3,4}};	int[,] arr = {{1,2},{3,4}}	int[][] arr = {{1,2},{3,4}}	arr = [[1,2],[3,4]]	let arr = [[1,2],[3,4]]	let arr: number[][] = [[1,2],[3,4]]
Access element	arr[0][1]	arr[0], arr[1,0]	arr[0], arr[1][0]	arr[0], arr[1][0]	arr[0], arr[1][0]	arr[0], arr[1][0]

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