const and const_cast

#include <iostream>
#include <stdio.h>
using namespace std;
class A{
public:
void fun(int& temp){cout<<"am inside fun()"<<endl;
temp = 2000;
printf("in fun() temp[%p] temp val[%d]\n",&temp, temp);
}
};





const int temp=100;



int main()
{
A a;
printf("in main() temp[%p] temp val[%d]\n",&temp, temp);
a.fun(const_cast<int&>(temp));
cout<<"temp:"<<temp<<endl;
}



This will generate an error. The reason is that the constant variable temp does not have physical storage:

http://stackoverflow.com/questions/8290132/is-memory-allocated-for-a-static-const-variable-whose-address-is-never-used




However, if you put temp inside main int main(){const int temp=100;...} Its behaviour will be large undefined. Since using const_cast to cast away const ness and reassign the value may or may not change the value itself.