How to Add Elements to a C# Dictionary?

C# Dictionary class constructor takes a key data type and a value data type. Both types are generic, so they can be any .NET data type.

· The following Dictionary class is a generic class and can store any data type.

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

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 below creates a dictionary where the key type is a string, and the value type is a short integer.

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

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 below creates a dictionary where the key type is a string, the value type is float, and the total number of items it can hold is 3.

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

PriceList.Add("Tea", 3.25f);

PriceList.Add("Juice", 2.76f);

PriceList.Add("Milk", 1.15f);

How to Retrieve Elements from a C# Dictionary?

· The Dictionary is a collection. So, we can use the foreach loop to go through all the items and read them using the Key ad Value properties. 

foreach (KeyValuePair<string, Int16> author in AuthorList)

{

    Console.WriteLine("Key: {0}, Value: {1}", author.Key, author.Value);

}

public void CreateDictionary()

{

    // Create a dictionary with string key and Int16 value pair

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

    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);

    // Read all data

    Console.WriteLine("Authors List");

    foreach (KeyValuePair<string, Int16> author in AuthorList)

    {

        Console.WriteLine("Key: {0}, Value: {1}", author.Key, author.Value);

    }

}

· The Dictionary class has three properties – Count, Keys, and Values.

How do you get the number of elements in a C# dictionary?

· The Count property gets the number of key/value pairs in a dictionary.

Console.WriteLine("Count: {0}", AuthorList.Count);

How to get an item from a C# dictionary?

· The Item property gets and sets the value associated with the specified key. 

// Set Item value

AuthorList["Mahesh Chand"] = 20;

// Get Item value

Int16 age = Convert.ToInt16(AuthorList["Mahesh Chand"]);

· How do you get a collection of keys in a C# dictionary?

· he Keys property gets a collection containing the keys in the Dictionary. It returns an object of KeyCollection type

// Get and display keys

Dictionary<string, Int16>.KeyCollection keys = AuthorList.Keys;

foreach (string key in keys)

{

    Console.WriteLine("Key: {0}", key);

}

How to get the collection of values of a C# dictionary?

· The Values property gets a collection containing the values in the Dictionary. It returns an object of ValueCollection type. 

// Get and display values

Dictionary<string, Int16>.ValueCollection values = AuthorList.Values;

foreach (Int16 val in values)

{

    Console.WriteLine("Value: {0}", val);

}