Quote from cppreference: Even though const_cast may remove constness or volatility from any pointer or reference, using the resulting pointer or reference to write to an object that was declared const or to access an object that was declared volatile invokes undefined behavior. So yes, modifying constant variables is undefined behavior. The output you see … Read more
You are not allowed to const_cast variables that are actually const. This results in undefined behavior. const_cast is used to remove the const-ness from references and pointers that ultimately refer to something that is not const. So, this is allowed: int i = 0; const int& ref = i; const int* ptr = &i; const_cast<int&>(ref) … Read more
const_cast is safe only if you’re casting a variable that was originally non-const. For example, if you have a function that takes a parameter of a const char *, and you pass in a modifiable char *, it’s safe to const_cast that parameter back to a char * and modify it. However, if the original … Read more