Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • World
  • Users
  • Groups
Skins
  • Light
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (No Skin)
  • No Skin
Collapse
Code Project
  1. Home
  2. General Programming
  3. C#
  4. convert part of a list to an array

convert part of a list to an array

Scheduled Pinned Locked Moved C#
data-structurestutorial
21 Posts 8 Posters 0 Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • A a fatemeh

    Hi; I want to convert a list to an array but just part of it,because my array is smaller than the list.

    int[] copyselection = (int[])selec.ToArray(typeof(int[]));

    I want to limit the array elements for example ,I want to copy just 100 elements of it; Thank you all in advance

    T Offline
    T Offline
    taha bahraminezhad Jooneghani
    wrote on last edited by
    #8

    list items have a index, you can use for for selecting 100 item, or if you looking at some value in items use list.Where(p => p.StartsWith("s")) in a Foreach loop.some thing like this:

    List<string> lsi = new List<string>();
    lsi.Add("sara");
    lsi.Add("soo");
    lsi.Add("kabab");
    foreach (var item in lsi.Where(p => p.StartsWith("s")))
    {
    Response.Write(item);
    }

    1 Reply Last reply
    0
    • A a fatemeh

      Hi; I want to convert a list to an array but just part of it,because my array is smaller than the list.

      int[] copyselection = (int[])selec.ToArray(typeof(int[]));

      I want to limit the array elements for example ,I want to copy just 100 elements of it; Thank you all in advance

      L Offline
      L Offline
      Luc Pattyn
      wrote on last edited by
      #9

      With all the upvoted answers so far, you haven't gotten the proper solution yet IMO; I recommend

      int[] mySmallArray=myList.GetRange(startIndex, count).ToArray();

      which avoids both a big intermediate array and any visible looping, and doesn't require .NET version 3.5+ :)

      Luc Pattyn [My Articles] Nil Volentibus Arduum

      D V 2 Replies Last reply
      0
      • V VJ Reddy

        Good answer. 5!

        L Offline
        L Offline
        Luc Pattyn
        wrote on last edited by
        #10

        you're too generous. :-D

        Luc Pattyn [My Articles] Nil Volentibus Arduum

        V 1 Reply Last reply
        0
        • V VJ Reddy

          Good answer. 5!

          L Offline
          L Offline
          Luc Pattyn
          wrote on last edited by
          #11

          you're really too generous. :-D

          Luc Pattyn [My Articles] Nil Volentibus Arduum

          1 Reply Last reply
          0
          • Richard Andrew x64R Richard Andrew x64

            Best answer! :thumbsup:

            The difficult we do right away... ...the impossible takes slightly longer.

            L Offline
            L Offline
            Luc Pattyn
            wrote on last edited by
            #12

            so far, yes. :laugh:

            Luc Pattyn [My Articles] Nil Volentibus Arduum

            1 Reply Last reply
            0
            • L Luc Pattyn

              With all the upvoted answers so far, you haven't gotten the proper solution yet IMO; I recommend

              int[] mySmallArray=myList.GetRange(startIndex, count).ToArray();

              which avoids both a big intermediate array and any visible looping, and doesn't require .NET version 3.5+ :)

              Luc Pattyn [My Articles] Nil Volentibus Arduum

              D Offline
              D Offline
              Dave Kreskowiak
              wrote on last edited by
              #13

              You sir, are too modest.

              Luc Pattyn wrote:

              and any visible looping

              Way to cover your ass! ;) Curiously, I'll have to dig into the GetRange code now...

              A guide to posting questions on CodeProject[^]
              Dave Kreskowiak

              L D 2 Replies Last reply
              0
              • D Dave Kreskowiak

                You sir, are too modest.

                Luc Pattyn wrote:

                and any visible looping

                Way to cover your ass! ;) Curiously, I'll have to dig into the GetRange code now...

                A guide to posting questions on CodeProject[^]
                Dave Kreskowiak

                L Offline
                L Offline
                Luc Pattyn
                wrote on last edited by
                #14

                I'm sure you'll find a loop inside, as well as inside List.ToArray() and Array.Copy(). And even if List.GetRange() were returning an IEnumerable rather than a list, there still would be a loop doing the hard work. :)

                Luc Pattyn [My Articles] Nil Volentibus Arduum

                1 Reply Last reply
                0
                • L Luc Pattyn

                  With all the upvoted answers so far, you haven't gotten the proper solution yet IMO; I recommend

                  int[] mySmallArray=myList.GetRange(startIndex, count).ToArray();

                  which avoids both a big intermediate array and any visible looping, and doesn't require .NET version 3.5+ :)

                  Luc Pattyn [My Articles] Nil Volentibus Arduum

                  V Offline
                  V Offline
                  VJ Reddy
                  wrote on last edited by
                  #15

                  Really good answer. 5!

                  L 1 Reply Last reply
                  0
                  • L Luc Pattyn

                    you're too generous. :-D

                    Luc Pattyn [My Articles] Nil Volentibus Arduum

                    V Offline
                    V Offline
                    VJ Reddy
                    wrote on last edited by
                    #16

                    Thank you :-D

                    1 Reply Last reply
                    0
                    • A a fatemeh

                      Hi; I want to convert a list to an array but just part of it,because my array is smaller than the list.

                      int[] copyselection = (int[])selec.ToArray(typeof(int[]));

                      I want to limit the array elements for example ,I want to copy just 100 elements of it; Thank you all in advance

                      A Offline
                      A Offline
                      Apocalypse Now
                      wrote on last edited by
                      #17

                      Use ArrayList. example: ArrayList AryObj= new ArrayList(); for (int i=0; i < selec.Item.Count; i++) { AryObj.Add(selec.Item[i].Text); }

                      L 1 Reply Last reply
                      0
                      • V VJ Reddy

                        Really good answer. 5!

                        L Offline
                        L Offline
                        Luc Pattyn
                        wrote on last edited by
                        #18

                        IMO you're right! :)

                        Luc Pattyn [My Articles] Nil Volentibus Arduum

                        1 Reply Last reply
                        0
                        • A Apocalypse Now

                          Use ArrayList. example: ArrayList AryObj= new ArrayList(); for (int i=0; i < selec.Item.Count; i++) { AryObj.Add(selec.Item[i].Text); }

                          L Offline
                          L Offline
                          Luc Pattyn
                          wrote on last edited by
                          #19

                          That is bad. ArrayList is the only list that existed back in .NET 1.0 and 1.1; since 2.0 we have generic lists such as List<int> and there is no real use for ArrayList anymore, it is just an equivalent to List<object> and therefore it is superfluous as a type. Furthermore it does not contribute at all to the solution of the OP's problem. :|

                          Luc Pattyn [My Articles] Nil Volentibus Arduum

                          A 1 Reply Last reply
                          0
                          • D Dave Kreskowiak

                            You sir, are too modest.

                            Luc Pattyn wrote:

                            and any visible looping

                            Way to cover your ass! ;) Curiously, I'll have to dig into the GetRange code now...

                            A guide to posting questions on CodeProject[^]
                            Dave Kreskowiak

                            D Offline
                            D Offline
                            DaveyM69
                            wrote on last edited by
                            #20

                            I've just seen this and happened to have reflector open so I've had a look! GetRange uses Array.Copy to copy to a new list:

                            List list = new List(count);
                            Array.Copy(this._items, index, list._items, 0, count);
                            list._size = count;
                            return list;

                            as is ToArray but to an array instead:

                            T[] destinationArray = new T[this._size];
                            Array.Copy(this._items, 0, destinationArray, 0, this._size);
                            return destinationArray;

                            Now quite what Array.Copy is doing I'm not 100% sure as it's an extern function, so perhaps it's using unmanaged code to block copy?

                            Dave
                            Binging is like googling, it just feels dirtier. Please take your VB.NET out of our nice case sensitive forum. Astonish us. Be exceptional. (Pete O'Hanlon)
                            BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

                            1 Reply Last reply
                            0
                            • L Luc Pattyn

                              That is bad. ArrayList is the only list that existed back in .NET 1.0 and 1.1; since 2.0 we have generic lists such as List<int> and there is no real use for ArrayList anymore, it is just an equivalent to List<object> and therefore it is superfluous as a type. Furthermore it does not contribute at all to the solution of the OP's problem. :|

                              Luc Pattyn [My Articles] Nil Volentibus Arduum

                              A Offline
                              A Offline
                              Apocalypse Now
                              wrote on last edited by
                              #21

                              Thanks :)

                              1 Reply Last reply
                              0
                              Reply
                              • Reply as topic
                              Log in to reply
                              • Oldest to Newest
                              • Newest to Oldest
                              • Most Votes


                              • Login

                              • Don't have an account? Register

                              • Login or register to search.
                              • First post
                                Last post
                              0
                              • Categories
                              • Recent
                              • Tags
                              • Popular
                              • World
                              • Users
                              • Groups