When and why const_cast is necessary for converting non-const to const types?
Why in the following code const-cast is necessary for line 8 and unnecessary for lines
6, 7, 9?
int a = 27; // 1
int const b = 412; // 2
int* pa = &a; // 3
int const c = a; // 4
int d = b; // 5
int const* p1 = pa; // 6
int* const* p2 = &pa; // 7
int const** p3 = const_cast<int const**>(&pa); // 8
int const* const* p4 = &pa; // 9
Please answer both questions or provide a link to the explanation:)