C# Dictionary

In C#, a dictionary is a collection type that is used to store elements as key-value pairs. Each key-value pair is known as an entry. The keys must be unique and cannot be null, whereas the values can be null or duplicate.

The Dictionary<TKey, TValue> class is the generic implementation of a dictionary in C#. The TKey and TValue parameters represent the data types of the keys and values, respectively.

Here's an example of how to create and use a dictionary in C#:

// Creating a dictionary with string keys and int values
Dictionary<string, int> myDictionary = new Dictionary<string, int>();

// Adding entries to the dictionary
myDictionary.Add("apple", 1);
myDictionary.Add("banana", 2);
myDictionary.Add("cherry", 3);

// Accessing the value associated with a key
int value = myDictionary["banana"];
Console.WriteLine(value);  // Output: 2

// Modifying the value associated with a key
myDictionary["cherry"] = 4;

// Removing an entry from the dictionary
myDictionary.Remove("apple");

// Iterating over the entries in the dictionary
foreach (KeyValuePair<string, int> entry in myDictionary)
{
    Console.WriteLine(entry.Key + ": " + entry.Value);
}

This would output:

banana: 2
cherry: 4