What is the correct type to use for an array index?

Question

This code works, but I want to explicitly declare the type of the index range max. However uX or iX, where X = 8, 16 or 32 gives compi

Answer 1

The compiler gives you a note about this:

   = note: slice indices are of type `usize`

You must index a slice with a usize. usize is an unsigned integral type that has the same size as a pointer, and can represent a memory offset or the size of an object in memory. On 32-bit systems, it's a 32-bit integer, and on 64-bit systems, it's a 64-bit integer. Declare your index variables as usize unless you really have a lot of them, in which case you can use x as usize to cast them to an usize.

When you leave out the type annotation, Rust deduces that your integer literals must be of type usize because slices implement Index and not Index or Index.