"Selecting" Instances of Classes

Ok, so I have a class called wpawn (making a chess game) and have instances of wpawn called wpawn1 through wpawn8 (8 pawns on a chess board per side). I have a function that can "select" a piece by changing a private data member in the class, "bool selected," from 0 to 1. All other instances should be at 0, so only 1 piece can be selected at a time. Now I wish to manipulate just that one instance of the wpawn class. How do I do this without creating code explicitly for each instance seperately?

It depends on how your code is set up. One possible answer is to create a function that takes a wpawn reference (or pointer, but reference is better). Pass the appropriate wpawn instance to the function.

I think instead of creating 8 seperate objects.. why not create an array of objects.. that way you can access any instances of the pawn class just by using an array index.

Ahh! An array! Why didn't I think of that? yes, that would solve the problem.

Thanks for the help! :)

One quick question, I had a nice constructor for the old set up that took 2 values (x and y coordinates). I'm new to using arrays and classes in conjunction, so how exactly would I initialize the instances in the array without creating new member functions? Just not sure of the syntax or procedure.

[EDIT]
If that didn't make sense, lemme reword it:

How do you initialize an array of instances of a class?
[/EDIT]

You can only use the default constructor for arrays of classes, provide some sort of 'set' function.

UPDATE:

I have narrowed down my problem to using class arrays as function inputs. So...how do you use class arrays as function inputs?

also, to Orbitz: http://cplus.about.com/od/beginnerct.../aa073002c.htm

I followed his model and now I can ditch that ugly initialization function! :D

"class wpawn[8]" ? Don't you want to name your variable something? The 'class' is also not required in C++. Why not use a loop by the way?

yea, ignore that earlier post, I completely replaced it.

you also bring up a good point. The name of the instance and the name of the class were the same. I have changed that now so that the class is wpawn and the array is whitepawn[8]. Sorry for the confusion.

[EDIT]
THANKS ORBITZ! your second sentence made me realize that I shouldn't be using "class" as the identifier, but rather the name of that class, wpawn. so now it reads:

Code:

---

void findpiece(wpawn whitepawn[8], int x, int y);

---

instead of

Code:

---

void findpiece(class whitepawn[8], int x, int y);

---

Thanks again! :)

the 8 is also completely useless. wpan whitepan[8] == wpawn whitepawn[] == wpawn *whitepawn in the context of *function parameters*. The C++ Tutorial you listed does not seem very standards compliant to me. I am too lazy right now the check the C++ standard but I doubt what it says works in strict mode. If you use g++ you should always compile with -W -Wall -ansi -pedantic. I do not know how to do the equivalent in VC++

hmm... I already changed my code over to that tut's format. I'm using VC++ 6.0. what's g++? I'm very new to advanced compiling.

and, strangely, it seems like only the 1st 3rd 5th and 7th pawns are being made! :confused:

Here's that new format I'm using from the site I was saying earlier:

Code:

---

wpawn whitepawn[9]={wpawn(1,2),wpawn(2,2),wpawn(3,2),wpawn(4,2),wpawn(5,2),wpawn(6,2),wpawn(7,2),wpawn(8,2)};

---

bump...

does anyone know why my program doesn't create all 8 instances, only the 1st 3rd 5th and 7th?

also:

Code:

---

xcoord = whitepawn[looper2].givexposition;
ycoord = whitepawn[looper2].giveyposition;

---

givexposition returns an int, and xcoord is type int, yet it gives me the following error:

C:\PROGRAM FILES\MICROSOFT VISUAL STUDIO\MYPROJECTS\SnSChess\main.cpp(238) : error C2440: '=' : cannot convert from 'int (__thiscall chesspiece::*)(void)' to 'int'
Conversion is a valid standard conversion, which can be performed implicitly or by use of static_cast, C-style cast or function-style cast
C:\PROGRAM FILES\MICROSOFT VISUAL STUDIO\MYPROJECTS\SnSChess\main.cpp(239) : error C2440: '=' : cannot convert from 'int (__thiscall chesspiece::*)(void)' to 'int'
Conversion is a valid standard conversion, which can be performed implicitly or by use of static_cast, C-style cast or function-style cast

[EDIT]

fixed it :P... I was forgetting the () after the function :p

givexposittion is a function, it would probably help to call it.

If you have an array then it has created all of them. Please show us how you discovered it only creates the odd values.