C# Join Two Lists Together

  1. C# Program to Join Two Lists Together Using AddRange() Method
  2. C# Program to Join Two Lists Together Using Enumerable.Concat() Method
  3. C# Program to Join Two Lists Together Using foreach Loop Method

The List is a data structure to store and process data. We can perform various useful operations on Lists.

In C#, there are multiple methods to add items to Lists, remove items from Lists and various other operations. But in some cases, we need to join already existing Lists together.

In this article, we are going to discuss some methods by which we can join two existing Lists together. Let’s check out these methods.

C# Program to Join Two Lists Together Using AddRange() Method

The method AddRange() is used to add two Lists. It adds the second List to the first List. The List to be added is passed as a parameter to this method.

The correct syntax to use this method is as follows:

AnyList.AddRange(ListToAdd);

Example Code:

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> Fruits = new List<string>() { "Apple", "Banana", "Orange", "Mango" };
        List<string> Vegetables = new List<string>() { "Potato", "Tomato", "Cauli Flower", "Onion" };
        Fruits.AddRange(Vegetables);
        Console.Write("Fruits and Vegetables are: ");
        Console.WriteLine(String.Join(",", Fruits));
    }
}

Output:

Fruits and Vegetables are: Apple,Banana,Orange,Mango,Potato,Tomato,Cauli Flower,Onion

C# Program to Join Two Lists Together Using Enumerable.Concat() Method

The method Enumerable.Concat() is a LINQ class method. It is used to concatenate two Lists together. The List that is to be added is passed as a parameter to this method.

The correct syntax to use this method is as follows:

AnyList.Concat(ListToAdd);

Example Code:

using System;
using System.Linq;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> Fruits = new List<string>() { "Apple", "Banana", "Orange", "Mango" };
        List<string> Vegetables = new List<string>() { "Potato", "Tomato", "Cauli Flower", "Onion" };
        List<string> FruitsAndVegetables = Fruits.Concat(Vegetables).ToList();
        Console.Write("Fruits and Vegetables are: ");
        Console.WriteLine(String.Join(",", FruitsAndVegetables));
    }
}

Output:

Fruits and Vegetables are: Apple,Banana,Orange,Mango,Potato,Tomato,Cauli Flower,Onion

C# Program to Join Two Lists Together Using foreach Loop Method

The foreach loop method is a traditional method, using which we can perform any operation on any data structure or data type. In this case, we have used a foreach loop to concatenate two Lists together. The foreach loop will add items one by one in each iteration.

The correct syntax to use foreach loop to add two Lists is as follows:

ListToAdd.foreach(AnyList => AnyList.Add(AnyList));

Example Code:

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> Fruits = new List<string>() { "Apple", "Banana", "Orange", "Mango" };
        List<string> Vegetables = new List<string>() { "Potato", "Tomato", "Cauli Flower", "Onion" };
        Vegetables.ForEach(Fruit => Fruits.Add(Fruit));
        Console.Write("Fruits and Vegetables are: ");
        Console.WriteLine(String.Join(",", Fruits));
    }
}

Output:

Fruits and Vegetables are: Apple,Banana,Orange,Mango,Potato,Tomato,Cauli Flower,Onion

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