c++ - difference between const and static keyword in function header

Consider the following code:

class Test
{
public:
   //1
   int kon1() const;

   //2
   const int kon2();

   //3
   static int kon3();
};

As far as I know, the difference between function 1 and 2 is that :

Function 1 says that the function will not be able to change any data member's value
Function 2 says that it will return a const int

(If I have wrong understanding, please correct me)

My question is : As we can see there, if we want to make a function to be const function, the const keyword is placed behind. But why in function 3, the static function, the static keyword is placed in front?

Solution

For const member functions must have the const keyword afterwards to avoid ambiguity with the return type.

For static, virtual and other keywords having a dramatic effect on how the function works, it's desirable to list it first so it's easier to see in the class definition. For example, we can quickly scan through a list of member functions and spot all the static functions, or all the virtual ones - aiding our understanding of the overall use of the function.

Marking a member function const (or e.g. an override) is a less crucial distinction - if you have a non-const object you can invoke functions whether they're const or not, the appropriate const-ness is often obvious to the reading developer as they absorb the function return type and identifier, and in some corporate/project coding standards mutating functions are grouped above const-accessors, or const and non-const versions of the same member function are side by side to emphasise their similarities - then the differet const-ness stands out more.

All these factors combine to make the actual choices in C++ optimal for development, but you're right in observing that they're a bit inconsistent.