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Conversion of System.Array to List


Question

Last night I had dream that the following was impossible. But in the same dream, someone from SO told me otherwise. Hence I would like to know if it it possible to convert System.Array to List

Array ints = Array.CreateInstance(typeof(int), 5);
ints.SetValue(10, 0);
ints.SetValue(20, 1);
ints.SetValue(10, 2);
ints.SetValue(34, 3);
ints.SetValue(113, 4);

to

List<int> lst = ints.OfType<int>(); // not working
2014/06/08
1
282
6/8/2014 10:15:07 AM

Accepted Answer

Save yourself some pain...

using System.Linq;

int[] ints = new [] { 10, 20, 10, 34, 113 };

List<int> lst = ints.OfType<int>().ToList(); // this isn't going to be fast.

Can also just...

List<int> lst = new List<int> { 10, 20, 10, 34, 113 };

or...

List<int> lst = new List<int>();
lst.Add(10);
lst.Add(20);
lst.Add(10);
lst.Add(34);
lst.Add(113);

or...

List<int> lst = new List<int>(new int[] { 10, 20, 10, 34, 113 });

or...

var lst = new List<int>();
lst.AddRange(new int[] { 10, 20, 10, 34, 113 });
2018/01/25
434
1/25/2018 2:51:39 AM

There is also a constructor overload for List that will work... But I guess this would required a strong typed array.

//public List(IEnumerable<T> collection)
var intArray = new[] { 1, 2, 3, 4, 5 };
var list = new List<int>(intArray);

... for Array class

var intArray = Array.CreateInstance(typeof(int), 5);
for (int i = 0; i < 5; i++)
    intArray.SetValue(i, i);
var list = new List<int>((int[])intArray);
2009/10/21

Interestingly no one answers the question, OP isn't using a strongly typed int[] but an Array.

You have to cast the Array to what it actually is, an int[], then you can use ToList:

List<int> intList = ((int[])ints).ToList();

Note that Enumerable.ToList calls the list constructor that first checks if the argument can be casted to ICollection<T>(which an array implements), then it will use the more efficient ICollection<T>.CopyTo method instead of enumerating the sequence.

2016/08/28

The simplest method is:

int[] ints = new [] { 10, 20, 10, 34, 113 };

List<int> lst = ints.ToList();

or

List<int> lst = new List<int>();
lst.AddRange(ints);
2014/11/24

In the case you want to return an array of enums as a list you can do the following.

using System.Linq;

public List<DayOfWeek> DaysOfWeek
{
  get
  {
    return Enum.GetValues(typeof(DayOfWeek))
               .OfType<DayOfWeek>()
               .ToList();
  }
}
2016/04/05

You can do like this basically:

int[] ints = new[] { 10, 20, 10, 34, 113 };

this is your array, and than you can call your new list like this:

 var newList = new List<int>(ints);

You can do this for complex object too.

2017/07/18

Source: https://stackoverflow.com/questions/1603170
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