Associative array

Introduction:

Associative arrays, also known as maps, symbol tables, or dictionaries, are a fundamental data structure in computer science and programming. They allow for efficient storage and retrieval of data using key-value pairs. In this article, we will delve into the concept of associative arrays, understand their operations, and explore practical code examples in popular programming languages such as C#, JavaScript, Python, and PHP.

Understanding Associative Arrays:

An associative array is an abstract data type that stores a collection of (key, value) pairs, where each key is unique within the collection. This means that for every key, there is at most one corresponding value. This characteristic makes associative arrays extremely useful in scenarios where fast lookup and retrieval of values based on keys is required.

Operations on Associative Arrays:

Addition of a Pair:

Associative arrays allow for the addition of a new (key, value) pair to the collection. This operation is typically performed using the key as the identifier and assigning the corresponding value to it. Let’s explore how this is done in different programming languages.

var dictionary = new Dictionary<string, int>();
dictionary.Add("apple", 5);emoval of a Pair:

const map = new Map();
map.set("apple", 5);

$array = [];
$array["apple"] = 5;

Removing of a Pair:

Associative arrays allow for the removal of a specific (key, value) pair from the collection. This operation is typically performed by specifying the key to be removed.

dictionary.Remove("apple");

map.delete("apple");

del dictionary["apple"]

unset($array["apple"]);

dictionary = {}
dictionary["apple"] = 5

Modification of an Existing Pair:

Associative arrays allow for the modification of the value associated with an existing key in the collection. This operation is performed by referencing the key and updating its corresponding value.

dictionary["apple"] = 10;

map.set("apple", 10);

dictionary["apple"] = 10

$array["apple"] = 10;

Lookup of a Value:

Associative arrays provide a fast lookup mechanism to retrieve the value associated with a specific key. This operation is performed by referencing the key.

int value = dictionary["apple"];

const value = map.get("apple");

value = dictionary["apple"]

$value = $array["apple"];

Links

Code Examples

C#
using System;
using System.Collections.Generic;

var dictionary = new Dictionary<string, int>();

dictionary.Add("apple", 5);
dictionary.Add("banana", 3);
dictionary.Add("orange", 8);

Console.WriteLine(dictionary["apple"]); // Output: 5
Console.WriteLine(dictionary["banana"]); // Output: 3
Console.WriteLine(dictionary["orange"]); // Output: 8

JavaScript
const map = new Map();

map.set("apple", 5);
map.set("banana", 3);
map.set("orange", 8);

console.log(map.get("apple")); // Output: 5
console.log(map.get("banana")); // Output: 3
console.log(map.get("orange")); // Output: 8

Python
dictionary = {}

dictionary["apple"] = 5
dictionary["banana"] = 3
dictionary["orange"] = 8

print(dictionary["apple"]) # Output: 5
print(dictionary["banana"]) # Output: 3
print(dictionary["orange"]) # Output: 8

PHP
$array = [];

$array["apple"] = 5;
$array["banana"] = 3;
$array["orange"] = 8;

echo $array["apple"]; // Output: 5
echo $array["banana"]; // Output: 3
echo $array["orange"]; // Output: 8

Conclusion