How do I copy items from list to list without foreach?

Question

How do I transfer the items contained in one List to another in C# without using foreach?

Answer 1

You could try this:

List<Int32> copy = new List<Int32>(original);

or if you're using C# 3 and .NET 3.5, with Linq, you can do this:

List<Int32> copy = original.ToList();

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I see that this answer is still getting upvotes. Well, here's a secret for ya: the above answer is still using a foreach. Please don't upvote this any further.

Answer 2

To add the contents of one list to another list which already exists, you can use:

targetList.AddRange(sourceList);

If you're just wanting to create a new copy of the list, see the top answer.

Answer 3

For a list of elements

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

lstTest.Add("test1");
lstTest.Add("test2");
lstTest.Add("test3");
lstTest.Add("test4");
lstTest.Add("test5");
lstTest.Add("test6");

If you want to copy all the elements

List<string> lstNew = new List<string>();
lstNew.AddRange(lstTest);

If you want to copy the first 3 elements

List<string> lstNew = lstTest.GetRange(0, 3);

Answer 4

And this is if copying a single property to another list is needed:

targetList.AddRange(sourceList.Select(i => i.NeededProperty));

Answer 5

This method will create a copy of your list but your type should be serializable.

Use:

List<Student> lstStudent = db.Students.Where(s => s.DOB < DateTime.Now).ToList().CopyList(); 

Method:

public static List<T> CopyList<T>(this List<T> lst)
    {
        List<T> lstCopy = new List<T>();
        foreach (var item in lst)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                BinaryFormatter formatter = new BinaryFormatter();
                formatter.Serialize(stream, item);
                stream.Position = 0;
                lstCopy.Add((T)formatter.Deserialize(stream));
            }
        }
        return lstCopy;
    }

Answer 6

Easy to map different set of list by linq without for loop

var List1= new List<Entities1>();

var List2= new List<Entities2>();

var List2 = List1.Select(p => new Entities2
        {
            EntityCode = p.EntityCode,
            EntityId = p.EntityId,
            EntityName = p.EntityName
        }).ToList();

Answer 7

Adding to the top answers, if you want copies of "the objects in the list", then you can use Select and make the copies. (While the other answers make "a copy of a list", this answer makes "a list of copies").

Suppose your item has a Copy method:

List<MyObject> newList = oldList.Select(item => item.Copy()).ToList();

Or that you can create a new object from the previous one with a constructor:

List<MyObject> newList = oldList.Select(item => new MyObject(item)).ToList();   

The result of Select is an IEnumerable<MyObject> that you can also pass to AddRange for instance, if your goal is to add to an existing list.

Answer 8

public static List<string> GetClone(this List<string> source)
{
    return source.Select(item => (string)item.Clone()).ToList();
}

Answer 9

OK this is working well From the suggestions above GetRange( ) does not work for me with a list as an argument...so sweetening things up a bit from posts above: ( thanks everyone :)

/*  Where __strBuf is a string list used as a dumping ground for data  */
public List < string > pullStrLst( )
{
    List < string > lst;

    lst = __strBuf.GetRange( 0, __strBuf.Count );     

    __strBuf.Clear( );

    return( lst );
}

Answer 10

Here another method but it is little worse compare to other.

List<int> i=original.Take(original.count).ToList();