populating List<> using Array get wrong numbers

Question

I have simple class structure that has an array part of its fields. I want to store this class in a list. The problem is when adding additional class structures to the list it handles it as if it's a direct update and not referenced.

 public class TrayLayout
 {
      public int[] inerD { get; set; }

public class TrayLayout
 {
      public int[] inerD { get; set; }

      public TrayLayout(int[] inerD)
      {
           this.inerD = inerD;
       }
 }
 public partial class Form1 : Form
 {
      public List<TrayLayout> trayL = new List<TrayLayout>();
      public Form1()
      {
           InitializeComponent();
      }

      private void Form1_Load(object sender, EventArgs e)
      {
           int[] aa = new int[2];
           aa[0]=1;
           aa[1]=2;
           //add the new class to TrayLoayout
           trayL.Add(new TrayLayout(aa));
           aa[0]=3;
           aa[1]=4;
           //add the new class to TrayLoayout using input array
           trayL.Add(new TrayLayout(aa));
           aa[0]=5;
           aa[1]=6;
           //add the new class to TrayLoayout
           trayL.Add(new TrayLayout(aa));
           textBox1.Text = "the numbers accepted \n"+ trayL[0].inerD[0].ToString() + " , " +trayL[0].inerD[1].ToString() + " \n" + trayL[1].inerD[0].ToString() + " , " +trayL[1].inerD[1].ToString() + " \n" + trayL[2].inerD[0].ToString() + " , " +trayL[2].inerD[1].ToString() ;

      }

I get in TextBoxes it shows the last input 5,6 5,6 5,6 instead of 1,2 3,4 5,6. I must be missing something?

Puppy · Accepted Answer · 2012-04-01 11:55:12Z

2

You always refer to the same int array, overwriting the previous values.

answered Apr 1, 2012 at 11:55

Puppy

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Comments

Gero · Accepted Answer · 2012-04-01 12:00:30Z

0

You have created 1 ArrayObject aa. And you are overwriting the first 2 values, when you assign 3 and 4. And when you assign 5 and 6 you have overwritten 3 and 4.

Create 3 different arrays or make aa[0] to aa[5].

answered Apr 1, 2012 at 12:00

Gero

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Comments

nickd · Accepted Answer · 2012-04-01 12:22:24Z

0

Assigning the int array to the TrayLayout class does not make a copy. Each instance of the TrayLayout class in your example has a reference to the same array, so when you update it following the call to the TrayLayout constructor, all your instances of TrayLayout see the same values.

Either copy the array internally in the TrayLayout constructor, or (as others are suggesting) use different arrays in the constructor calls.

answered Apr 1, 2012 at 12:22

nickd

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2 Comments

user1306240 Over a year ago

I tried in the constractor public TrayLayout(int[] ainerD) { this.inerD[0] = ainerD[0]; this.inerD[1] = ainerD[1]; } and nothing was writin

nickd Over a year ago

You are still only capturing a reference. Use something like this.inerD = new int[ainerD.Length]; Array.Copy(ainerD, this.inerD, ainerD.Length);

Arion · Accepted Answer · 2012-04-01 15:53:24Z

0

You need to replace this:

int[] aa = new int[2];
aa[0]=1;
aa[1]=2;
//add the new class to TrayLoayout
trayL.Add(new TrayLayout(aa));
aa[0]=3;
aa[1]=4;
//add the new class to TrayLoayout
trayL.Add(new TrayLayout(aa));
aa[0]=5;
aa[1]=6;
//add the new class to TrayLoayout
trayL.Add(new TrayLayout(aa));

With this:

trayL.Add(new TrayLayout(new int[]{1,2}));
trayL.Add(new TrayLayout(new int[]{3,4}));
trayL.Add(new TrayLayout(new int[]{5,6}));

Edit

You could do it like this:

var start=1;
var end=13;
trayL.Add(new TrayLayout(Enumerable.Range(start,end).ToArray()));

edited Apr 1, 2012 at 15:53

answered Apr 1, 2012 at 12:14

Arion

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3 Comments

user1306240 Over a year ago

what if I have an array 0f 53 that will be heck of coding is there a simple way

user1306240 Over a year ago

trayL.Add(new TrayLayout(new int[]{1,2,3,4,5,6,7,8,9,10,11,12,13})); and so on... not convenint

user1306240 Over a year ago

Arion 10X 4 the comment but what I shown here is a recreate of the problam, where in the project I have to store 10 barcodes or in other case 53 barcodes IN AN ARRAY and store the class in List<> so is there a esay way to store the data?

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