Difference between a List's Add and Append method in C#?

Difference between a List's Add and Append method in C#?

In C#, List is a collection type that can be used to store elements of any type in a sequence. Add and Append are both methods of the List class, but they have different behavior:

  • List.Add() method is used to add a single element to the end of a List. It returns void and takes one argument that represents the element to be added.

Example:

var myList = new List<string>(); myList.Add("apple"); myList.Add("banana");

In this example, the Add method is used to add two elements to myList.

  • List.Append() method is used to append one or more elements to the end of a List. It returns an IEnumerable<T> and takes one or more arguments that represent the elements to be appended.

Example:

var myList = new List<string>(); myList = myList.Append("apple").Append("banana").ToList();

In this example, the Append method is used to append two elements to myList. Notice that we are re-assigning the result of Append back to myList. ToList() is used to convert the IEnumerable<T> returned by Append to a List.

In summary, List.Add() is used to add a single element, while List.Append() is used to append one or more elements to a list.

Examples

  1. C# List Add Method

    • Description: Explains the basic usage of the Add method in a List to add a single element.
    • Code Implementation:
      // List Add method for adding a single element List<int> myList = new List<int>(); myList.Add(42);

  2. C# List Append Method

    • Description: Introduces the concept of an Append method in a List and how it differs from Add.
    • Code Implementation:
      // Custom Append method for adding a single element to a List public static class ListExtensions { public static void Append<T>(this List<T> list, T item) { list.Add(item); } } // Usage List<int> myList = new List<int>(); myList.Append(42);

  3. C# List Add vs Append with Single Element

    • Description: Compares using Add and a custom Append method when adding a single element to a List.
    • Code Implementation:
      // Comparing List Add vs Append with a single element List<int> myList = new List<int>(); myList.Add(42); // Using Add myList.Append(42); // Using custom Append

  4. C# List AddRange Method

    • Description: Demonstrates using the AddRange method in a List to add multiple elements from a collection.
    • Code Implementation:
      // List AddRange method for adding multiple elements List<int> myList = new List<int>(); List<int> elementsToAdd = new List<int> { 1, 2, 3 }; myList.AddRange(elementsToAdd);

  5. C# List AppendRange Method

    • Description: Introduces the concept of an AppendRange method in a List for adding multiple elements.
    • Code Implementation:
      // Custom AppendRange method for adding multiple elements to a List public static class ListExtensions { public static void AppendRange<T>(this List<T> list, IEnumerable<T> items) { list.AddRange(items); } } // Usage List<int> myList = new List<int>(); List<int> elementsToAdd = new List<int> { 1, 2, 3 }; myList.AppendRange(elementsToAdd);

  6. C# List AddRange vs AppendRange with Multiple Elements

    • Description: Compares using AddRange and a custom AppendRange method when adding multiple elements to a List.
    • Code Implementation:
      // Comparing List AddRange vs AppendRange with multiple elements List<int> myList = new List<int>(); myList.AddRange(new List<int> { 1, 2, 3 }); // Using AddRange myList.AppendRange(new List<int> { 4, 5, 6 }); // Using custom AppendRange

  7. C# List Add for Insertion

    • Description: Demonstrates using Add for inserting an element at a specific index in a List.
    • Code Implementation:
      // List Add for insertion at a specific index List<string> myList = new List<string> { "Item1", "Item2" }; myList.Add("Item3"); // Adding at the end myList.Insert(1, "ItemInserted"); // Inserting at index 1

  8. C# List Append for Dynamic Elements

    • Description: Illustrates using a custom Append method for dynamically adding elements to a List.
    • Code Implementation:
      // List Append for dynamically adding elements public static class ListExtensions { public static void Append<T>(this List<T> list, T item) { list.Add(item); } } // Usage List<string> myList = new List<string>(); string dynamicElement = "DynamicItem"; myList.Append(dynamicElement);

  9. C# List Add for Unique Elements

    • Description: Shows using Add for ensuring unique elements in a List.
    • Code Implementation:
      // List Add for ensuring unique elements List<int> myList = new List<int>(); int elementToAdd = 42; if (!myList.Contains(elementToAdd)) { myList.Add(elementToAdd); }

  10. C# List Append for Fluent Syntax

    • Description: Introduces a custom Append method for a fluent syntax when adding elements to a List.
    • Code Implementation:
      // List Append for fluent syntax public static class ListExtensions { public static List<T> Append<T>(this List<T> list, T item) { list.Add(item); return list; } } // Usage List<string> myList = new List<string>(); myList.Append("Item1").Append("Item2").Append("Item3");

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