CODEWITHSUNDEEP
c#
Magicco
Magicco

Reputation: 41

Why does the .NET Array.Resize() method use an ref argument?

Other methods like Array.Sort() don't use ref and yet they change the array.

Also this code confuses me:

using System.Linq;
using System;

namespace jmennyprostor {
    public static void Main(string[] args)
    {
        int[] mojepole = {4,4,5,2,4};
        pole.changearray(mojepole); // this does change mojepole
        pole.resizearray(mojepole); // this magically does not change mojepole
        pole.resizearrayworking(ref mojepole); // this DOES change mojepole
    }

    public class pole 
    {
        public static void changearray(int[] polerole)
        {
            polerole[2] = 44444;
        }

        public static void resizearray(int[] polerole)
        {
            Array.Resize(polerole);
        }

        public static void resizearrayworking(ref int[] polerole)
        {
            Array.Resize(polerole);
        }
    }
}

Upvotes: 0

Views: 369

Answers (1)

David Browne - Microsoft
David Browne - Microsoft

Reputation: 89361

Because the array may not actually be resized. So you pass in a reference to an array of size N, and the method may allocate a new array of size newSize and change your reference to point to the new array.

It has a similar effect as

oldArray = Array.Resize(oldArray, newSize);

if the method returned a reference to the new array instead of using a ref argument.

Upvotes: 2

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