How to change an array in a function without changing the original array? [duplicate]

Question

In C# and many other languages, if you pass an array to a function it passes the pointer/reference which means you can change the value of an array from inside a function.

From Microsoft:

Arrays can be passed as arguments to method parameters. Because arrays are reference types, the method can change the value of the elements.

I have a special case where I need to access and change an array's contents from a function but I do not want to change the original array. I thought this would be quite simple. I could set a new array equal to the old array and change the new array. This acts the same, however, because the new array is just a pointer to the old one.

static void AddToArray(string[] array) {
    var newArray = array;
    newArray[2] = "y";
}

static void Main(string[] args) {
    string[] array = new string[5];
    array[0] = "h";
    array[1] = "e";

    AddToArray(array);

}

If you print the contents of array at each step:

"he"
"hey" (inside function)
"hey" (after function call)

I've done a lot of research online but somehow haven't found many other people who needed help with this. Advice is greatly appreciated!

umesh shukla · Accepted Answer · 2021-10-14 02:12:09Z

1

You are not creating your array using "new" Keyword inside function. Change below line -

var newArray = array;

To

var newArray = new string[args.Length];

and after creating this as a new array, you can copy the values from args (passed) array

edited Oct 14, 2021 at 2:12

answered Oct 14, 2021 at 2:05

umesh shukla

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