lapis grotto
I am confused by the type []const u8, from the official document the statements regarding const is few. []const u8 is a slice, and is a ptr and length,but what's the diff from []u8. the length is const or the ptr is const or both. another point is each element of slice is const u8, but what is const u8,it is a type or else. I know what is const identifier and pointer, but confused by the type with const.
except the const in the slice type, any other usage?
prisma leaf
const is a modification of the pointer, it means that the values pointed to are const
[]u8 is a slice of mutable u8s (you can change them)
[]const u8 is a slice of constant u8s (you can't change them)
the ptr and length may or may not be mutable depending on whether you store the slice as a var or const
fiery shadow
var var_const: []const u8 = ...;
var_const = other;
var_const.ptr = other_ptr;
var_const.len = other_len;
// var_const[i] = 0;
const const_mut: []u8 = ...;
// const_mut = other;
// const_mut.ptr = other_ptr;
// const_mut.len = other_len;
const_mut[i] = 0;
And then mix and match
Btw, to respond to another part of the question: const u8 isn't a type that exists. See, the way it works is that const and similar qualifiers aren't attributes of the type, but rather attributes of the memory representing the type
It's sort of like the difference between describing a category vs an instance of that category. It isn't correct to say "human eyes are blue", but it would be correct to say "these humans in particular have blue eyes"