System.Array 到 List 的转换

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

Answer 1

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 });

Answer 2

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);

Answer 3

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.

Answer 4

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);

Answer 5

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();
  }
}

Answer 6

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.

Answer 7

in vb.net just do this

mylist.addrange(intsArray)

or

Dim mylist As New List(Of Integer)(intsArray)

Answer 8

You can just give it try to your code:

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);

int[] anyVariable=(int[])ints;

Then you can just use the anyVariable as your code.

Answer 9

I know two methods:

List<int> myList1 = new List<int>(myArray);

Or,

List<int> myList2 = myArray.ToList();

I'm assuming you know about data types and will change the types as you please.

Answer 10

Just use the existing method.. .ToList();

   List<int> listArray = array.ToList();

KISS(KEEP IT SIMPLE SIR)

Answer 11

I hope this is helpful.

enum TESTENUM
    {
        T1 = 0,
        T2 = 1,
        T3 = 2,
        T4 = 3
    }

get string value

string enumValueString = "T1";

        List<string> stringValueList =  typeof(TESTENUM).GetEnumValues().Cast<object>().Select(m => 
            Convert.ToString(m)
            ).ToList();

        if(!stringValueList.Exists(m => m == enumValueString))
        {
            throw new Exception("cannot find type");
        }

        TESTENUM testEnumValueConvertString;
        Enum.TryParse<TESTENUM>(enumValueString, out testEnumValueConvertString);

get integer value

        int enumValueInt = 1;

        List<int> enumValueIntList =  typeof(TESTENUM).GetEnumValues().Cast<object>().Select(m =>
            Convert.ToInt32(m)
            ).ToList();

        if(!enumValueIntList.Exists(m => m == enumValueInt))
        {
            throw new Exception("cannot find type");
        }

        TESTENUM testEnumValueConvertInt;
        Enum.TryParse<TESTENUM>(enumValueString, out testEnumValueConvertInt);