problem with keyword const

[kai2005]

please take a look of this program, how can this be explained?

#include <iostream>
#include <cstdlib>
using namespace std;

int main()
{
  const int i=0;
  int * j=(int*)&i;  
  const int k=0;
  int * u=(int*)&k;
  *j+=1;
  *u+=1;
  cout<<i<<"   "<<*j<<endl;
  cout<<&i<<" "<<j<<endl;
  cout<<k<<"   "<<*u<<endl;
  cout<<&k<<" "<<u<<endl;
  system("pause");
  return 0;
}

 

[cpjust]

A similar question was answered a while back. Here's the link:

http://www.tek-tips.com/viewthread.cfm?qid=1166241

 

[ArkM]

If a program attempts to access the stored value of an object through an lvalue of other than one of the following types the behavior is undefined:
--- a long list w/o (cast-expression const ptr => ptr) ---

So

const int k;
int * u=(int*)&k;

is semantically legal sequence until you try to modify k via *u. There are program cases where it's necessary (or useful) to get not-const pointer to a const object (especially in legacy codes).
Yes, it's a nasty taste but it's not an interesting case.
The language can't (and should not) prevent all programmer's errors. Remember the most reliable aircraft with ferro-concrete wings...
Moreover, the implementation can place k var in read-only storage (but should not to do that).
Well, let's see:

int a[2];
f(a);
....
void f(int a[])
{
... 
  a[2] = 0;
...

Oh, what's a terrible language defect, place a ban on array indexing!...