read only array ?

SUNIL GUTTA

Hello

Well i want to declare an array as read only so once initialized we cant change it ..

like ReadOnly int [] arr ={1,2,3,4,5};

is it possible like this ???? if not please provide remedy

Thank you

3 Replies

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Vulpes13y ago
Accepted answer
It's possible to make an array read-only by wrapping it in a ReadOnlyCollection.

For example:

using System;
using System.Collections.ObjectModel;

class Test
{
static void Main()
{
int [] arr ={1,2,3,4,5};
var roarr = new ReadOnlyCollection(arr);
roarr[0] = 6; // compiler error : cannot be assigned to, it's read only
Console.ReadKey();
}
}
Vulpes13y ago
The ReadOnlyCollection doesn't have any built-in Sort() method and it would be impossible to write one because, having sorted the contents, you would be unable to assign them back to the collection!

All you can do is to copy them back out to an array again and then sort that:

using System;
using System.Collections.ObjectModel;

class Test
{
static void Main()
{
int [] arr ={2,1,4,3,5};
var roarr = new ReadOnlyCollection(arr);
int[] arr2 = new int[roarr.Count];
roarr.CopyTo(arr2, 0);
Array.Sort(arr2);
foreach(int i in arr2) Console.Write("{0} ", i);
Console.WriteLine();
Array.Reverse(arr2);
foreach(int i in arr2) Console.Write("{0} ", i);
Console.WriteLine();
Console.ReadKey();
}
}

You could wrap the sorted array again in a ReadOnlyCollection but it would, of course, be a different object to the one that was used originally.
SUNIL GUTTA13y ago
well i want an array say s1 to be declared as read-only and can it be sorted in asc/dsc and printable ????

TY