Destroy an element of an array

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Hello there, i have an array that containe those data

C#

int [] marks = new int[5]  { 1, 2, 3, 4, 5};

i want to destroy the seconde ellement the "2"

and i want to get my array like thise
marks =  { 1,  3, 4, 5, 0};

or marks ={1,3,4,5}

please help

What I have tried:

Hello there, i have an array that containe those data

C#

int [] marks = new int[5]  { 1, 2, 3, 4, 5};

i want to destroy the seconde ellement the "2"

and i want to get my array like thise
marks =  { 1,  3, 4, 5, 0};

or marks ={1,3,4,5}

please help

Posted 31-May-16 6:06am

Jammes_Ca

Updated 31-May-16 8:22am

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Afzaal Ahmad Zeeshan 31-May-16 12:56pm

Just use a generic list of integer type and remove the element that you don't want. Very less people use static arrays now a days.

Philippe Mori 31-May-16 20:52pm

You should not use an array if you want to modify it. Use a list instead. By the way, in .NET a list is essentially a resizable array.

If you need an array later in code, then convert back to an array once all modifications are done. If it is your own code, it would be preferable to refactor it to use list everywhere you need to modify the number of items after creation.

Essentially, you should always try to select the container that is the most appropriate for the problem.

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Matt T Heffron · Accepted Answer · 2016-05-31T07:09:00

If you must modify an array in place then when you delete an element, you need to copy all of the following elements down one position, and put the zero at the end position:

C#

int [] marks = new int[5]  { 1, 2, 3, 4, 5};
int deleteAtIndex = 1;
for (int i = deleteAtIndex; i < marks.Length - 1; ++i)
{
  marks[i] = marks[i + 1];
}
marks[marks.Length - 1] = 0;

There is no way to resize an array in place.

If you can just create a new array with the element removed then there are several ways to do this:
(Starting with the same marks array and deleteAtIndex as above.)

C#

int [] marksNew = new int[marks.Length-1];
for (int i = 0, j = 0; i < marks.Length; ++i, ++j)
{
  if (i != deleteAtIndex)
    marksNew[j] = marks[i];
  else
    ++i;  
}
marks = marksNew;

or (using Linq):

C#

marks = marks.Where((_, ix) => ix != deleteAtIndex).ToArray();

or using generic List:

C#

List<int> temp = new List<int>(marks);
temp.RemoveAt(deleteAtIndex);
marks = temp.ToArray();

Edit:
It wasn't clear if you want to remove the element based on knowing the position in the array or the value of the element. The above assume that you know the position (index) of the element to be removed. If you want to remove an element based on its value, then (for the in place removal):

C#

int deleteValue = 2;
int deletedCount = 0;
for (int i = 0, j = 0; i < marks.Length; ++i, ++j)
{
  int mi = marks[i];
  if (mi != deleteValue)
  {
    marks[j] = mi;
  }
  else
  {
    ++i;
    ++deletedCount;
  }
}
for (int i = 0, j = marks.Length - 1; i < deletedCount; ++i, --j)
  marks[j] = 0;

for the replacement array case:

C#

marks = marks.Where(v => v != deleteValue).ToArray();

or using generic List:

C#

List<int> temp = new List<int>(marks);
temp.Remove(deleteValue);
marks = temp.ToArray();

As Afzaal Ahmad Zeeshan said in the initial comments, using a generic List instead of an array (if you can) makes this much easier.

phil.o · Accepted Answer · 2016-05-31T06:50:00

You cannot "destroy an element of an array". First, an array is something immutable in .NET, if you want to modify its size you will have to create a new one and copy the data. Moreover, your array contains only int values, which are value types, and there is no concept of destroying a value type.

Your best option is to use Linq extensions for that:

C#

int [] marks = new int[5]  { 1, 2, 3, 4, 5};
return marks.Where(v => v != 2).ToArray(); // You get {1,3,4,5}

Karthik_Mahalingam · Accepted Answer · 2016-05-31T06:48:00

try this

C#

int removeItem = 2;
int[] marks = new int[5] { 1, 2, 3, 4, 5 };
marks = marks.Where(k => k != removeItem).ToArray();

Note : add the reference

C#

using System.Linq;

Remove based on position, take care of validation.

C#

int position = 2;
int[] marks = new int[5] { 1, 2, 3, 4, 5 };
var temp = marks.ToList();
temp.RemoveAt(position-1);
marks = temp.ToArray();

PraveenDora · Accepted Answer · 2016-05-31T07:11:00

any reason you dont want use ArayList instead Array ?.. below code converts Array to ArrayList and converts back Array finally destroys Arraylist Obj ..

if you use array List ..all need

C#

al.RemoveAt(1);

for ur requirement

C#

int[] marks = new int[5] { 1, 2, 3, 4, 5 };

      ArrayList al= new ArrayList();

      al.AddRange(marks);
      al.RemoveAt(1);

      marks = (int[])al.ToArray(typeof(int));

      al.Clear();
      al = null;

Destroy an element of an array

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