How to Convert Integer Array to List in C#? - GeeksforGeeks

28 May, 2020
We have given a integer array arr and the task is to convert integer array into the list lst in C#. In order to do this task, we have the following methods:
Method 1:  List<T> class: This represents the list of objects which can be accessed by index. It comes under the System.Collection.Generic namespace. List<T> class also provides the methods to search, sort, and manipulate lists. And this is also used to convert a given an integer array to the list .
Syntax:
List<int> lst = new List<int> { 1, 2, 3};

Example:
C#
// C# program to convert a // given an integer array // to the listusing System;using System.Text;using System.Collections.Generic;using System.Linq;  public class GFG{        static void Main(string[] args)    {        // given integer array         // { 10, 20, 30, 40, 50 }                  // using List<T> class        List<int> lst = new List<int> { 10, 20, 30, 40, 50 };                  // you can write the above line of code as          // int[] ints = new [] { 10, 20, 30, 40, 50 };        // List<int> lst = ints.OfType<int>().ToList();                // printing output        foreach (int i in lst)        {          Console.Write(i + " ");        }      }}
Output:
10 20 30 40 50

Method 2:  List<T>(IEnumerable<T>) Constructor : Using this constructor a new instance of the List<T> class can be  initialize that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied. Thus this can also be used to convert a given an integer array to the list .
Syntax:
List<int> lst = new List<int>(integer_array);

Example:
C#
// C# program to convert a // given an integer array // to the listusing System;using System.Text;using System.Collections.Generic;using System.Linq;  public class GFG{          static List<int> get_list(int[] arr)     {        // List<T>(IEnumerable<T>)         // Constructor        // is a used to convert a         // given an integer array         // to the list              List<int> L = new List<int> (arr);                  return L;    }        static void Main(string[] args)    {        // given integer array        int[] arr = { 10, 20, 30, 40, 50 };                  // function calling        List<int> lst = get_list(arr);                  // printing output        foreach (int i in lst)        {          Console.Write(i + " ");        }      }}
Output:
10 20 30 40 50

Method 3:  AddRange(IEnumerable<T>) Method : This method is used to add the elements of the specified collection to the end of the List<T>. Thus this can also be used to convert a given an integer array to the list.
Syntax:
List<int> lst = new List<int>();
lst.AddRange(integer_array)

Example:
C#
// C# program to convert a // given an integer array // to the listusing System;using System.Text;using System.Collections.Generic;using System.Linq;  public class GFG{          static List<int> get_list(int[] arr)     {        // AddRange(IEnumerable<T>)         // Method is a used to convert        // given an integer array         // to the list              List<int> L = new List<int>();        L.AddRange(arr);                  return L;    }        static void Main(string[] args)    {        // given integer array        int[] arr = { 10, 20, 30, 40, 50 };                  // function calling        List<int> lst = get_list(arr);                  // printing output           foreach (int i in lst)        {          Console.Write(i + " ");        }        }}
Output:
10 20 30 40 50

Method 4:  ToList() Method: The Enumerate.Tolist method is from System.Linq Namespace which creates a List<T> from an IEnumerable<T>. It returns a List<T> that contains elements from the input sequences.
Syntax:
List<int> lst = integer_array.ToList();

Example:
C#
// C# program to convert a // given an integer array // to the listusing System;using System.Text;using System.Collections.Generic;using System.Linq;  public class GFG{          static List<int> get_list(int[] arr)     {        // ToList() Method is a used         // to convert a given an         // integer array to the list              List<int> L = arr.ToList();                  return L;    }        static void Main(string[] args)    {        // given integer array        int[] arr = { 10, 20, 30, 40, 50 };                  // function calling        List<int> lst = get_list(arr);                  // printing output          foreach (int i in lst)        {          Console.Write(i + " ");        }    }}
Output:
10 20 30 40 50

Method 5:  Add() Method : This method is used to add an object to the end of the List. Thus this can also be used to convert a given an integer array to the list .
Syntax:
List<int> lst = new List<int>();
lst.Add(int val);

Example:
C#
// C# program to convert a // given an integer array // to the listusing System;using System.Text;using System.Collections.Generic;using System.Linq;  public class GFG{          static List<int> get_list(int[] arr)     {        // Add() Method is a used         // to convert a given an         // integer array to the list              List<int> L = new List<int>();                  for(int i = 0 ; i < arr.Length ; i++)        {            L.Add(arr[i]);        }                  return L;    }        static void Main(string[] args)    {        // given integer array        int[] arr = { 10, 20, 30, 40, 50 };                  // function calling        List<int> lst = get_list(arr);                  // printing output        foreach (int i in lst)        {          Console.Write(i + " ");        }    }}
Output:
10 20 30 40 50

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