The type that’s meant for indexing in C and C++ is called `size_t`. It is pointer-sized. In Rust it’s called `usize` and Rust does not have implicit conversions

The type that’s meant for indexing in C and C++ is called `size_t`. It is pointer-sized. In Rust it’s called `usize` and Rust does not have implicit conversions, so if you accidentally use too narrow an integer type to compute an index, at least Rust forces you to add an explicit cast somewhere.