List Fundamentals

Add, remove, access — the everyday bread-and-butter operations

The essential operations on dynamic arrays (Python list, JS Array, Java ArrayList, Go slice, C++ vector).

Language:

Python

All languages — Create & fill

JavaScript

// Leer
const nums = [];

// Mit Werten
const nums2 = [1, 2, 3];

// Vorgefüllt (5 Nullen)
const zeros = new Array(5).fill(0);   // [0,0,0,0,0]

// 2D (3×3 Matrix)
const matrix = Array.from({ length: 3 }, () => new Array(3).fill(0));

TypeScript

const nums: number[] = [];
const nums2: number[] = [1, 2, 3];

const zeros: number[] = new Array(5).fill(0);

const matrix: number[][] = Array.from({ length: 3 }, () => new Array(3).fill(0));

Java

// Array (feste Größe):
int[] arr = new int[5];        // [0,0,0,0,0]
int[] arr2 = {1, 2, 3};

// ArrayList (dynamisch):
List<Integer> list = new ArrayList<>();
List<Integer> list2 = new ArrayList<>(Arrays.asList(1, 2, 3));

// Slice (dynamisch):
var nums []int                   // nil slice
nums2 := []int{1, 2, 3}

// Vorgefüllt:
zeros := make([]int, 5)          // [0,0,0,0,0]

// 2D:
matrix := make([][]int, 3)
for i := range matrix {
    matrix[i] = make([]int, 3)
}

C++

// Array (feste Größe):
int arr[5] = {};               // {0,0,0,0,0}

// Vector (dynamisch):
vector<int> nums;
vector<int> nums2 = {1, 2, 3};

// Vorgefüllt:
vector<int> zeros(5, 0);       // {0,0,0,0,0}

// 2D:
vector<vector<int>> matrix(3, vector<int>(3, 0));