How to create a dictionary in C#

Introduction

A dictionary type represents a collection of keys and values pair of data.

The Dictionary class defined in the System.Collections.Generic namespace is a generic class and can store any data types in a form of keys and values. Each key must be unique in the collection. Before you use the Dictionary class in your code, you must import the System.Collections.Generic namespace using the following line.

using System.Collections.Generic; 

Creating a Dictionary

The Dictionary class constructor takes a key data type and a value data type. Both types are generic so it can be any .NET data type. 

The following The Dictionary class is a generic class and can store any data types. This class is defined in the code snippet creates a dictionary where both keys and values are string types. 

Dictionary<string, string> EmployeeList = new Dictionary<string, string>(); 

The following code snippet adds items to the dictionary.  

EmployeeList.Add("Mahesh Chand", "Programmer");
EmployeeList.Add("Praveen Kumar", "Project Manager");
EmployeeList.Add("Raj Kumar", "Architect");
EmployeeList.Add("Nipun Tomar", "Asst. Project Manager");
EmployeeList.Add("Dinesh Beniwal", "Manager"); 

The following code snippet creates a dictionary where the key type is string and value type is short integer. 

Dictionary<string, Int16> AuthorList = new Dictionary<string, Int16>(); 

The following code snippet adds items to the dictionary.  

AuthorList.Add("Mahesh Chand", 35);
AuthorList.Add("Mike Gold", 25);
AuthorList.Add("Praveen Kumar", 29);
AuthorList.Add("Raj Beniwal", 21);
AuthorList.Add("Dinesh Beniwal", 84); 

We can also limit the size of a dictionary. The following code snippet creates a dictionary where the key type is string and value type is float and total number of items it can hold is 3.   

Dictionary<string, float> PriceList = new Dictionary<string, float>(3); 

The following code snippet adds items to the dictionary.  

PriceList.Add("Tea", 3.25f);
PriceList.Add("Juice", 2.76f);
PriceList.Add("Milk", 1.15f);

 

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