C# List Example - Collection Types

In my previous article I explained about the difference between Collection Types - C# Generic List and ArrayList. So, In short  an array does not resize dynamically whereas a List does. With it, you do not need to manage the size on your own. 

Using List in C#

List is a generic (constructed) type. You need to use <angel bracket> in the List declaration. It may any element like int, string, class etc. But a List can also hold reference types and object instances.

C# List Example Code

C# List Methods

There are following methods are available in C# List such as Add(), AddRange(), Clear(), Contains(), Exists(), IndexOf() etc. Here I will explain use of these methods in brief.

C# List Add

You can add new item to a List using c# list add() method. The below example adds a int type to a List collection.

static void Main(string[] args)

        {

            List<int> list = new List<int>();

            list.Add(11);

            list.Add(32);

            list.Add(53);

            list.Add(74);

        }

Note: If we need to add an array to list we use the AddRange() method.

Getting value from C# List

You can read value from a List using list foreach or by for loop. The below shows that how to retrieve values from a List. 

foreach (int num in list) // Loop through List with foreach

            {

                Console.WriteLine(num);

              

            }

for (int i = 0; i < list.Count; i++) // Loop through List with for

            {

                Console.WriteLine(list[i]);

            }

C# Count List

To get the number of elements in your List, access the Count property. Use the Clear() method, along with the Count property, to erase all the elements in a List.

Convert Array To List - C#

If you need to convert an array to list, find the example below:

int[] arr = new int[3]; // New array with 3 elements

            arr[0] = 21;

            arr[1] = 31;

            arr[2] = 51;

            List<int> list = new List<int>(arr); // Copy to List

            Console.WriteLine(list.Count);       // 3 elements in List

C# List Find

You can find any item in your list by using foreach loop, find the example below:

// New list for example

            List<int> listNum = new List<int>(new int[] { 2, 3, 5 });

            // See if List contains 3

            foreach (int number in listNum)

            {

                if (number == 3) // Will match once

                {

                    Console.WriteLine("Contains 3");

                }

            }

There are some alternative methods available in List like Contains(), Exists(), IndexOf(). 

• Contains() returns only a bool.
• Exists() receives a Predicate and returns a bool.
• IndexOf() returns the position of the element found. 

C# List Join - Convert List<string> to comma-separated string

This is helpful when you need to turn several strings into one comma-delimited string. It requires the ToArray instance method on List. Have a look into this example below:

// List of cities we need to join

            List<string> cities = new List<string>();

            cities.Add("New Delhi");

            cities.Add("London");

            cities.Add("Meerut");

            cities.Add("Kolkata");

            // Join strings into one CSV line

            string line = string.Join(",", cities.ToArray());

            Console.WriteLine(line);

C# List GetRange

You can get a range of elements in your List using the GetRange method. Find the example below:

List<string> rivers = new List<string>(new string[]

                                          {

                                              "nanu",

                                              "yamuna",     // River 2

                                              "gangotri",    // River 3

                                              "yamnotri",

                                              "yellow"

                                          });

            // Get rivers 2 through 3

            List<string> range = rivers.GetRange(1, 2);

              (string river in range)

            {

                Console.WriteLine(river);

            }

Conclusion : It was fun in learning and writing an article on C# List, Using List in C# and C# Convert Array to List. I hope this article will be helpful for enthusiastic peoples who are eager to learn and implement some interesting stuffs in new technology. 

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