What is the difference between const int*, int* const, and const int* const?

Question

Accepted Answer

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

```cpp
int x = 10;

const int* p1 = &x;  // Pointer to const
// *p1 = 20;  // Error
p1 = nullptr;  // OK

int* const p2 = &x;  // Const pointer
*p2 = 20;  // OK
// p2 = nullptr;  // Error

const int* const p3 = &x;  // Const pointer to const
// *p3 = 20;  // Error
// p3 = nullptr;  // Error
```

**Read right to left:**
- `int*` — pointer to int.
- `int* const` — const pointer to int.
- `const int*` — pointer to const int.

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