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C# Dictionary

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A Dictionary is a collection type that allows you to store key-value pairs. It is part of the System.Collections.Generic namespace.

 

The Dictionary<TKey, TValue> class provides fast lookups and is useful when you need to associate values with unique keys.

 

Here's a basic overview of how to use a Dictionary in C#.

 

Creating a Dictionary

You can create a dictionary by specifying the types for keys (TKey) and values (TValue).

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        // Creating a dictionary with string keys and int values
        Dictionary<string, int> myDictionary = new Dictionary<string, int>();

        // Adding key-value pairs
        myDictionary.Add("one", 1);
        myDictionary.Add("two", 2);
        myDictionary.Add("three", 3);

        // Accessing values by key
        Console.WriteLine(myDictionary["two"]); // Output: 2
    }
}

 

Initializing a Dictionary with Initial Values

You can initialize a dictionary with initial values using a collection initializer.

Dictionary<string, int> myDictionary = new Dictionary<string, int>
{
    { "one", 1 },
    { "two", 2 },
    { "three", 3 }
};

 

Checking if a Key Exists

You can check if a key exists in the dictionary before accessing its value to avoid exceptions.

if (myDictionary.ContainsKey("two"))
{
    int value = myDictionary["two"];
    Console.WriteLine(value); // Output: 2
}

 

Iterating Through a Dictionary

You can iterate through the keys and values of a dictionary using a foreach loop.

foreach (var kvp in myDictionary)
{
    Console.WriteLine($"Key: {kvp.Key}, Value: {kvp.Value}");
}

 

Removing Items from a Dictionary

You can remove items from a dictionary using the Remove method.

myDictionary.Remove("two");

 

More Dictionary Methods

The Dictionary<TKey, TValue> class provides various methods for working with dictionaries, such as TryGetValue, ContainsKey, Count, Clear, etc. You can explore these methods based on your requirements.

// Example of using TryGetValue
int value;
if (myDictionary.TryGetValue("two", out value))
{
    Console.WriteLine(value); // Output: 2
}

 

These are some basic operations you can perform with a C# Dictionary. It's a powerful and flexible data structure for handling key-value pairs efficiently.

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