CODEWITHSUNDEEP
c++static
user2531608
user2531608

Reputation: 141

why c++ does not accepts static keyword in function defnition?

I have a program where a class T has a static function.

static void T::func()
{
    m_i=10;
    cout<<m_i<<endl;
}

When I try to add static in function definition, the compiler throws error error: cannot declare member function ‘static void T::func()’ to have static linkage. Why is it not accepting static keyword in definition?

Upvotes: 2

Views: 308

Answers (2)

Some programmer dude
Some programmer dude

Reputation: 409356

The problem is that the keyword static means different things depending on context.

When you declare a member function to be static, like in

class T
{
    ...
    static void func();
    ...
};

Then the static keyword means that func is a class function, it's not bound to a specific object.

When you define the function in a source file, like

static void T::func() { ... }

Then you set the function linkage which is different from using static in a declaration inside a class. What static does when defining the function is to say that the function is only available in the current translation unit, and that contradicts the declaration that the function is available for all who knows the class.

It's simply not possible to make a member function (declared static or not) have static linkage.

If you want to "hide" the member function from others, so it can't be called, why not simply make it a private member function? You could also use things like the pimpl idiom or just not have it as a member function to begin with, in which case you can declare it to have static linkage.

Upvotes: 9

thorsan
thorsan

Reputation: 1064

You don't need static in implementation, only in definition.

T.h

class T
{  
    int m_i;
    static int s_i;
public:
    static void func();
};

T.cpp

int T:s_i = 0;

void T::func()
{ 
   // Access only static and local variables

   // I.e this is not allowed
   m_i=10;

   // This is allowed
   s_i=10;
}

Upvotes: 2

Related Questions