Initialize array in constructor's initialization list

Question

I'm trying to initialize an array in my constructor's intialization list, and I want the array to have the size MAX_SIZE, which is a public static const in my Stack class. How can I get it to work? The compiler complains, saying they have incompatible types in assignment of 'double' to 'double[0u]'

Here is my code:

class Stack {
 public: 
 Stack();
 static const unsigned MAX_SIZE; 
 private:
 double array[];
 unsigned elements; 
 }; // class Stack
 Stack::Stack(): array( array[MAX_SIZE] ), elements(0) {}
 const unsigned Stack::MAX_SIZE = 4;

Thanks in advance for your help.

• Jerry Coffin: Unless you're completely masochistic: static const unsigned max_size = 4; std::vector<double> array; Stack::Stack() : array(MAX_SIZE){}
• Sean: Is there a simpler way perhaps? i.e. without using vectors. How can I get the program to accept my array data member with its size being MAX_SIZE?
• Jerry Coffin: I would get used to using std::vector. I rarely use arrays; I'll use a std::vector be preference nearly every time. The code @Jesse Good has given should work as well.
• Anupam Srivastava: There are valid reasons to avoid vector. Vector always initializes on a heap while an array can be initialized over stack.

Answer 1

 class Stack {
 public:
 Stack();
 static const unsigned MAX_SIZE = 4;
 private:
 double array[MAX_SIZE];
 unsigned elements;
 }; // class Stack
 Stack::Stack(): array(), elements(0) {}

But, std::vector would be better as mentioned in the comments.

• Sean: I see.. so, basically, avoid initializing the array in the initialization list. Not possible, correct? Also, is it not possible to write my MAX_SIZE constant after main the way I did?
• Sean: Reason I ask is cause I read differently on here, that the definition should be outside of the class: publib.boulder.ibm.com/infocenter/comphelp/v8v101/…
• Jesse Good: array() in the intializer list zero initializes all the elements. You are correct, and I didn't define MAX_SIZE because I am only using it's value in the code. Define MAX_SIZE outside the class if you need to use it elsewhere.
• Jerry Coffin: @Sean: You don't need a separate definition for a static const <integer type> variable like you do in other cases.
• Jesse Good: @mezhaka: Yes, this form is called value initialization.