Re: basic question on c++ linking

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 29 Jun 2008 08:17:38 -0700 (PDT)
Message-ID:
<7f60b3c1-535b-4ad1-863c-bd3df745aeca@k37g2000hsf.googlegroups.com>
On Jun 29, 1:10 pm, Peskov Dmitry <vamsi.kom...@gmail.com> wrote:

On Jun 29, 3:04 pm, James Kanze <james.ka...@gmail.com> wrote:


    [...]

Let me put my question differently ? which one below

a)
class new_class;

or

b)
class new_class
{
        int a;
        public:
        new_class();
};

is a class declaration ?


Both. The second is also a definition. (A definition is a
declaration, but the reverse is not necessarily true.)

Because if i include (b) in my code as this one it works.


That's because the way you used the class required a definition.

using namespace std;
#include <iostream>

class new_class
{
        int a;
        public:
        new_class();
};

int main(){
        new_class st1;
        return 0;
}

I assume class definition includes the function that you are defining
something like
class new_class
{
        int a;
        public:
        new_class();
};


A class definition includes the contents (members) of the class.

new_class::new_class
{
         a = 10;
         }

is a class definition ?


No, that's a syntax error.

A class definition is:
    class <name> <baseclass-declarations>[opt] { ... } ;
A class declaration (which isn't also a definition) is just:
    class <name> ;

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