what are static functions in C++

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1.I have confusion in understanding why do we need static member functions? 2.What happens when we declare static member functions? 3.What does it means when static member functions have class scope or belong to class rather than objects of the class?

Posted 28-Feb-12 23:08pm

Abhinay Kumar

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3 solutions

Solution 3

In answer to question 1, "Why do we need static member functions?"

I've used them in the past when I wanted to use a member function as a WNDPROC.
Since you can't use a non-static method as the callback that WndProc is, you need to create a static method. Then from within that static method you must determine which c++ object instance is pertinant to the particular window.

The practise leaves one feeling a little unlean, and is known as Thunking.

I first came across this use in the source-code for Win32++[^]
I'd assume that similar code was found within MFC

Posted 28-Feb-12 23:49pm

enhzflep

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barneyman 29-Feb-12 18:15pm

Win callbacks, or thread-entry points

Anywhere else, and you get a withering look and a "please explain"

Solution 2

if you need to add some behavior which affect every instance of that class, static method and properties do it for you.

Posted 28-Feb-12 23:31pm

tssutha03

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OriginalGriff · Accepted Answer · 2012-02-28T23:13:00

Solution 1

Static functions are those that operate only on static data - they are not related to any instance of the class, and cannot access or call any non-static variables or functions. They do not have a this pointer.

You access trhen differently too - via the class name, rather than via an instance variable.

Posted 28-Feb-12 23:13pm

OriginalGriff

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Abhinay Kumar 29-Feb-12 5:26am

Is it possible to access them through objects of the class?If they do not have this pointer how is it possible to call them through objects of the class?

OriginalGriff 29-Feb-12 5:35am

You can call them through an instance, but it is not a good idea - it implies that they are non-static, which they aren't. Even if you do, they do not get a "this" pointer, so cannot access anything.
MyClass::MyStaticFunction();
is a lot more obvious than
myclassInstance.MyStaticFunction();