Few problems with your implementation:
- You are exposing both coinage and volume as writtable, meaning I can say
coinage = 100000; volumne = 0;
and your program will continue as if nothing was wrong. - You are requiring the user to calculate volume, don’t make your user do math you can do
- You aren’t actually allowing the user to tell you enough information to calculate volume. If I call addcoins with and amount of 25 cents, does that mean a quarter, 25 pennies, a nickel, etc.
- What are the
static readonly int
values for, and why would you make them an array? - Naming, unless your professor said otherwise, you should follow the naming guidelines put out by Microsoft.
I could go on, but this is hopefully enough to get you started on looking properly at what your real requirements are and how you are going to satisfy them.