Initialize c# array to its index value without loops or recursions?

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hey, i know that C# inits the array to the default(T) when is first initialized.
(int[] ar = new int[n]);

is there any way to initialize the array:
a[0] = 0
a[1] = 1
...
a[n] = n

without any loops or recursion?

thanks

by the way, my solution was similar to this:

public class intArray
{
  int[] arr;
  bool[] gotArray;

  public intArray(int size)
  {
    arr = new int[size];
    gotArray = new bool[size];
  }

  // dont remember exactly the [] syntax but:
  public int operator [](int index)
  {
     get
     {
        if (!gotArray[index])
           return index;
        else
           return arr[index];
     }
     set
     {
        arr[index] = value;
        gotArray[index] = true;
     }
     
  }

}

but it seems that there's a better solution

Posted 11-Aug-11 6:39am

arielb

Updated 11-Aug-11 7:00am

v2

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3 solutions

Solution 1

You mean something like:

int[] ar = new int[3] { 0, 1, 2 };

Posted 11-Aug-11 6:50am

Wendelius

Comments

arielb 11-Aug-11 12:55pm

nope, because u dont know whats the number of n, its variant.
if it would be constant then this initiazlization would be ok.

i got a tip to think more object oriented style.

Wendelius 11-Aug-11 13:17pm

You don't have to define the length so you can also use:
int[] ar = new int[] { 0, 1, 2 }
But this isn't what you're after?

arielb 11-Aug-11 13:24pm

no, you don't know the length of the array, u are getting that as a parameter.
means, what u have in ur hand is
int[] array = new int[n]

now, initialize it without a loop

Solution 2

C#

int[] ar = new int[3];
ar.Initialize();

Posted 11-Aug-11 7:16am

#realJSOP

Comments

arielb 11-Aug-11 13:26pm

no.. it inits everything to 0... not 0,1,2,3.. etc

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lewax00 · Accepted Answer · 2011-08-11T07:26:00

You could cut out the bool array in your original by using a nullable int

C#

public class intArray
    {
          int?[] arr;
           
          public intArray(int size)
          {
                arr = new int?[size];
          }

          public int this[int index]
          {
                get
                {
                    if (arr[index] == null)
                        arr[index] = index;
                    
                    return (int)arr[index];
                }
                set
                {
                    arr[index] = value;
                }
          }
    }


    class Program
    {
        static void Main(string[] arguments)
        {
            intArray iarr = new intArray(10);

            for (int i = 0; i < 10; ++i)
                Console.Out.WriteLine(iarr[i]);

            Console.ReadKey();
        }
    }