C++: What is the difference between const int*, int* const, and const int* const?

const int* — pointer to const. int const* — const pointer. const int const* — const pointer to const.

1int x = 10;
2const int* p1 = &x;  // Pointer to const
3int* const p2 = &x;  // Const pointer
4const int* const p3 = &x;  // Const pointer to const

• const int* — cannot modify value.
• int* const — cannot change pointer.
• const int* const — cannot modify either.