why const_cast is creating two values for one variable

Asked Jan 23 '17 at 07:27

Active Jan 23 '17 at 07:27

Viewed 26 times

I was reading about const_cast, as it is supposed to remove the constantness of the variable,

const int c1 = 100;
int *c2 = const_cast <int *>(&c1); // removing the constantness
*c2 = 200; // hence now i can edit it
cout << *c2 << endl; // reflect the changed value = 200
cout << c1 << endl; // still old value = 100

constantness is removed and variable i can edit, it is same like passing it to some function, which receives "int *" datatype,

but why same pointed space is showing two values?

Is const_cast is creating some other temporary space?

asked Jan 23 '17 at 07:27

Vishwadeep Singh

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Undefined behaviour. – juanchopanza Jan 23 '17 at 07:28
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Since `c1` is declared `const`, the compiler knows it can't change. So when it compiles the code `cout << c1`, it optimizes that to `cout << 100`. – Barmar Jan 23 '17 at 07:30
Take a look at the generated assembly code to see what's happening. – Barmar Jan 23 '17 at 07:32
Oh Okay, yes seems correct, because i am trying to modify a constant variable. Which is in compilers hand to behave. – Vishwadeep Singh Jan 23 '17 at 07:34

why const_cast is creating two values for one variable

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