con/destructor defaults

are any of these code blocks equivalent?

Code:

---

class c
{
    int x,y;
};

---

Code:

---

class c
{
    int x,y;
    c() {};
};

---

Code:

---

class c
{
    int x,y;
    c();
};

c::c(){}

---

edit: I almost forgot, the same question for destructors too.

No. :) Well, sort of.

The first one uses the built-in default constructor. I'm not sure how it's implemented, but it's probably the same as the second version.

The second one declares and implements the constructor inline. (Because the function body is inside the class.) When a function is inline, this suggests to the compiler (it can ignore the request) that the function is so simple that where ever it is used, the code in the function is put there instead of a function call to this trivial function. It's a good idea to make set and get functions as well as empty ones inline like that.

The last one makes the constructor like a normal function. But the compiler is free to optimise and make any functions inline that it thinks should be inline, and in fact most compilers ignore the inline suggestions by the programmer and make their own decisions. They're much better at it than we are. :)

So they're probably the same, in the end, with optimisations and all.

The the second one

Code:

---

c() {};

---

this ; is not required.

oh ok

Quote:

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Originally Posted by noobcpp

this ; is not required.

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oh, right. *smacks head*

I've just thought of another question: Are constructors/destructors supposed to have return types?

thanks :D

Simple Answer Nope
cause They Dont need.

Quote:

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Are constructors/destructors supposed to have return types?

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I believe the answer is no.

so it's impossible to have a function pointer to a constructor or a destructor?

Quote:

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so it's impossible to have a function pointer to a constructor or a destructor?

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I would reason yes, since constructors do not have names. Without a name, how would one point to a function?

ok I tried this

Code:

---

class c
{
public:
    int x,y;
    c();
};

c::c(){}

int main()
{
    typeof(c::c)*var;

    var=c::c;


    return 0;
}

---

Code:

---

main.cc: In function `int main()':
main.cc:14: error: expected primary-expression before ';' token

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what does that mean?

Quote:

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constructors do not have names

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Isn't it the same name as the class?

Quote:

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Isn't it the same name as the class?

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From what I understand, no. The syntax just happens to involve the class name, but it is really different from normal function declaration, even if it looks similiar.