C/C++ changing the value of a const

Question

I had an article, but I lost it. It showed and described a couple of C/C++ tricks that people should be careful. One of them interested me but now that I am trying to repli

Answer 1

Note any attempt to cast away constness is undefined by the standard. From 7.1.5.1 of the standard:

Except that any class member declared mutable can be modified, any attempt to modify a const object during its lifetime results in undefined behavior.

And right after this example is used:

const int* ciq = new const int (3);     //  initialized as required
int* iq = const_cast(ciq);        //  cast required
*iq = 4;                                //  undefined: modifies a  const  object

So in short what you want to do isn't possible using standard C++.

Further when the compiler encounters a declaration like

const int a = 3; // I promisse i won't change a

it is free to replace any occurance of 'a' with 3 (effectively doing the same thing as #define a 3)