Rust Essentials - Second Edition

References

In our previous example, m which had the value &n is the simplest form of pointer, called a reference (or borrowed pointer)--the variable m is a reference to the stack-allocated variable n and has type &i32 because it points to a value of type i32.

In general, when n is a value of type T, then the reference &n is of type &T.

Here n is immutable, so m is also immutable; trying to change the value of n through m with *m = 7; for example, results in an error:

    cannot assign to immutable borrowed content `*m`  

Rust does not let you change an immutable variable via its pointer, contrary to C.

Because there is no danger of changing the value of n through a reference, multiple references to an immutable value are allowed, they can only ...