Defining const in a class

Sorry if the question is rather elementary. You see, I've never defined constants with "const" keyword. I've always defined it in a macro. But apparently KDevelop can't recognize macro constant in the "CTRL+Space" hotkey (which is rather annoying). And defining the constants in global variables is a bad practice. So, the question is simple really, how do I define constants with "const typedef" keyword in a class? I've tried defining it in the ".h" and failed e.g.:

Code:

---

class a
{
private:
  const int c_iTheConst = 10000; //Failed!!!
};

---

Thanks in advance.

I think you have to initialize it with a member initializer like:

Code:

---

class a : c_iTheConst(10000)
{
private:
  const int c_iTheConst;
};

---

Edit: Ignore that, you use the member initializer in the constructor instead. My bad.

Translation:

Code:

---

class a
{
public:
        a() : c_iTheConst(10000) { }
private:
        const int c_iTheConst;
};

---

Note that I used a() : c_iTheConst(10000) { } and not a() { c_iTheConst = 100000; }

Thanks. But what if the constant was a struct?

You should give the struct a constructor that initialises its members in an initialisation list, then use something like this:

Code:

---

struct s
{
    s( const int m1_, const int m2_ ) : m1(m1_) , m2(m2_)
    {}
    const int m1;
    const int m2;
};

class a
{
public:
        a() : c_iTheConst(10000) , s(3030, 10349) { }
private:
        const struct s const_struct;
        const int c_iTheConst;
};

---

If the const has the same value for all instances of the class, then you should make it static as well. If it is a static const int, you should be able to initialize it in the class body (although some older compilers might not allow it). For the struct, I don't remember if you can initialize it in the class body or not, but either way if all instances are using the same const value it should be static.