How to declare an object const for one function and not for an other?

[trialanderror usually]

Helle there,

i got an global object and i got global functions. Both predefined.
How can i set the object const for one function and not for the other?

Thanks for the Answers.

[vlad from moscow]

The only way is to pass this object to the function as an argument through a parameter that declared either as const reference or as a local variable of the function. For example

#include <iostream>

int globalObject;

void f1( const int &x ) {  x = 1; }
void f2( int x ) { x = 2; }

int main()
{
   std::cout << "globalObject = " << globalObject << std::endl;

   f1( globalObject );
   f2( globalObject );

   std::cout << "globalObject = " << globalObject << std::endl;
}

[guestgulkan]

That's all seems pointless to me - the object is global - passing a reference to it, or a copy of it seems ...well ... pointless - it can be access directly anytime
from anywhere in the code.

[JLBorges]

> i got an global object and i got global functions. Both predefined.
> How can i set the object const for one function and not for the other?

You can't. http://en.wikipedia.org/wiki/One_Definition_Rule

[trialanderror usually]

The Point ist, that i either didnt declare the functions i have to define nor the main (That means the Interface is predefined). Furthermore i am not able to manipulate the main function.
I am writing a Plugin for another Programm, and that declares the functions it would like to have. (It works as a DLL)

Now i got no other choice as to define a global variable to exchange data from one function to another.
Thats the problem. And now i want to implement, that one function can read only, and another can manipulate.

The Question is: Is that even possible under these conditions.

[vlad from moscow]

It is possible if you will wrap the global variable in a class and the functions will be the class member functions one if which will have trailing const qualifier.:)

[trialanderror usually]

Yeah, it isnt optimal, but if its the only possibility i am going to do it that way. But nowadays i have some other trouble to fix first :)