Rust: What is the difference between raw pointers and references?

Raw pointers — unsafe, no guarantees. References — safe, guaranteed valid.

Raw pointers:

• *const T, *mut T.
• Unsafe to dereference.
• Can be null.
• No aliasing rules.

References:

• &T, &mut T.
• Safe to use.
• Never null.
• Aliasing rules.

1let x = 5;
2let r = &x;  // Reference
3let p = &x as *const i32;  // Raw pointer
4
5unsafe {
6    println!("{}", *p);  // Must be in unsafe block
7}

Key: Use references when possible, raw pointers only when necessary.