static function definition

[Senthilvel]

Hi all,
I was thinking that all static members(both data members and functions)
should be defined.
I try to use a static function without defining it
1. outside the class - it gives an error and thats is what i expected.
2. inside the class, ie inside another member function, but it compiles.Why
is that??

Does not the compiler need the definition of Init to generate the code for
Foo ???
I looked into the TCPPPL but didn't find an answer...Can somebody kindly
explain where my understanding
goes wrong ???

#include <iostream>

using namespace std;

class A
{
public:
static void Init();
void Foo() { Init(); }
};

int main()
{
A::Init(); --->Gives an error that Init is an unresolved external symbol.
A a;
a.Foo(); ---> Fine,Also gives an error.
return 0;
}


Here is the actual code that started my confusion..


template<class B,class D> class IsDerivedFrom1
{
class No{};

class Yes{ No no[2]; };
public:
static Yes Test(B* pb);
static No Test(...);

public:
enum { Is = sizeof(Test(sta tic_cast<D*>(0) )) > sizeof(No) };

};

Is the declaration of Test is enough to resolve the overload in the
initialisation of the
enum value Is ???

Thanks and Best Regards,
Senthilvel.

[John Harrison]

Re: static function definition


"Senthilvel " <Senthil@nospam .com> wrote in message
news:cb5orb$t8g $1@news.mch.sbs .de...[color=blue]
> Hi all,
> I was thinking that all static members(both data members and functions)
> should be defined.
> I try to use a static function without defining it
> 1. outside the class - it gives an error and thats is what i expected.
> 2. inside the class, ie inside another member function, but it[/color]
compiles.Why[color=blue]
> is that??
>
> Does not the compiler need the definition of Init to generate the code for
> Foo ???
> I looked into the TCPPPL but didn't find an answer...Can somebody kindly
> explain where my understanding
> goes wrong ???
>
> #include <iostream>
>
> using namespace std;
>
> class A
> {
> public:
> static void Init();
> void Foo() { Init(); }
> };
>
> int main()
> {
> A::Init(); --->Gives an error that Init is an unresolved external symbol.
> A a;
> a.Foo(); ---> Fine,Also gives an error.
> return 0;
> }
>
>
> Here is the actual code that started my confusion..
>
>
> template<class B,class D> class IsDerivedFrom1
> {
> class No{};
>
> class Yes{ No no[2]; };
> public:
> static Yes Test(B* pb);
> static No Test(...);
>
> public:
> enum { Is = sizeof(Test(sta tic_cast<D*>(0) )) > sizeof(No) };
>
> };
>
> Is the declaration of Test is enough to resolve the overload in the
> initialisation of the
> enum value Is ???
>[/color]

Yes it is. If you don't actually call Test, you don't need to define it.

john