The keyword for casting a value to a type.
as is most commonly used to turn primitive types into other primitive types, but it has other
uses that include turning pointers into addresses, addresses into pointers, and pointers into
let thing1: u8 = 89.0 as u8; assert_eq!('B' as u32, 66); assert_eq!(thing1 as char, 'Y'); let thing2: f32 = thing1 as f32 + 10.5; assert_eq!(true as u8 + thing2 as u8, 100);Run
In general, any cast that can be performed via ascribing the type can also be done using
so instead of writing
let x: u32 = 123, you can write
let x = 123 as u32 (Note:
let x: u32 = 123 would be best in that situation). The same is not true in the other direction, however,
as allows a few more coercions that aren't allowed implicitly, such as
changing the type of a raw pointer or turning closures into raw pointers.
as is used include as extra syntax for
use, to change the name
something is imported as.
For more information on what
as is capable of, see the Reference