如何为数组添加附加值？

Question

I am currently creating a program where the user can use a printer as long as that particular user has enough funds.

The current issue I am having is that if the user chooses to have colour printing instead of black and white then the price for each piece of paper goes up.

How do I add value to an already existing array?

Here is my code...

printers[0] = new Printer("printer1", 0.10M);
            printers[1] = new Printer("printer2", 0.08M);
            printers[2] = new Printer("printer3", 0.05M);
            printers[3] = new Printer("printer4", 0.15);
            printers[4] = new Printer("printer5", 0.09M);

            foreach (Printer r in mPrinters)
            {
                if (printer != null)
                    printerCombo.Items.Add(r.getName());
            }

Answer 1

Technically, you can Resize the array:

 Array.Resize(ref printers, printers.Length + 1);

 printers[printers.Length - 1] = new Printer("printer6", 0.25M);

However, a much better approach is to change the collection type: array into List<T> :

 List<Printer> printers = new List<Printer>() {
   new Printer("printer1", 0.10M),
   new Printer("printer2", 0.08M),
   new Printer("printer3", 0.05M),
   new Printer("printer4", 0.15),
   new Printer("printer5", 0.09M), }; 

 ...

 printers.Add(new Printer("printer6", 0.25M));

Answer 2

Arrays have fixed size - after you created array with size 10 you can't add one more element (to make size 11).

Use List<Printer> :

List<Printer> printers = new List<Printer>();
printers.Add(new Printer("printer2", 0.08M));
//add all items

Also you can access elements by index:

var element = printers[0];

Using List you can change its size, add and remove elements.

Answer 3

Arrays are fixed length. You need to copy the values into a new array or use an List, List<>, or ArraryList.