Dictionary

Comparison Between Array and Dictionary:

A dictionary is a collection of data values.
It holds a key: value pair in which we can easily access a value if the key is known.
It improves the readability of your code and makes it easier to debug
It is fast as the access of a value through a key is a constant time operation

Dictionary representation:

C++

// C++ program to demonstrate functionality of unordered_map
#include <iostream>
#include <unordered_map>
using namespace std;
 
int main()
{
     // Declare a Dictionary
    unordered_map<string, int> my_dict;
 
    // Adding Elements to the Dictionary
        my_dict["key1"] = 1;
        my_dict["key2"] = 2;
        my_dict["key3"] = 3;
 
    // Printing the Dictionary
    for (auto key : my_dict)
        cout << "Key: " << key.first << " Value: " << key.second << endl;
 
}
 
// This code is contributed by aadityaburujwale.

Java

/*package whatever //do not write package name here */
import java.io.*;
import java.util.*;
 
class GFG {
    public static void main (String[] args) {
        
          // Declare a Dictionary
        HashMap<String,Integer> my_dict = new HashMap<>();
       
         // Adding Elements to the Dictionary
        my_dict.put("key1", 1);
        my_dict.put("key2", 2);
        my_dict.put("key3", 3);
 
          // Printing the Dictionary
        for(String key:my_dict.keySet()) {
              System.out.println("Key: "+ key +", Value: " + my_dict.get(key));
            }
    }
}

Python

# Declaring and initializing a dictionary
my_dict = {
  "key1": 1,
  "key2": 2,
  "key3": 3
}
# Printing the dictionary
 
print(my_dict)

C#

using System;
using System.Collections.Generic;
public class GFG {
 
    static public void Main()
    {
     // Declare a Dictionary
        IDictionary<string, int> my_dict= new Dictionary<string, int>();
       
     // Adding Elements to the Dictionary
        my_dict.Add("key1", 1);
        my_dict.Add("key2", 2);
        my_dict.Add("key3", 3);
 
      // Printing the Dictionary
        foreach(var kvp in my_dict) {
          Console.WriteLine("Key: {0}, Value: {1}", kvp.Key, kvp.Value);
    }
  }
}

Javascript

<script>
// Javascript program to demonstrate functionality of map
 
// Declare a Dictionary
var my_dict = new Map();
 
// Adding Elements to the Dictionary
my_dict.set("key1", 1);
my_dict.set("key2", 2);
my_dict.set("key3", 3);
 
// Printing the Dictionary
console.log(my_dict);
 
// This  code is contributed by Shubham Singh
</script>

Output

{'key3': 3, 'key2': 2, 'key1': 1}

Time Complexity: O(1)
Auxiliary Space: O(1)

Differences between Array and Dictionary Data Structure

Tags:

#Java-Dictionary #Arrays #Data Structures #Difference Between #DSA #Arrays #Data Structures

Arrays:

Comparison Between Array and Dictionary:

Dictionary

Dictionary representation:

C++

Java

Python

C#

Javascript

Differences between Array and Dictionary Data Structure

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