[−]Keyword as
Cast between types, or rename an import.
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
other pointers.
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 as
,
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,
explicitly using 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.
Other places as
is used include as extra syntax for crate
and use
, to change the name
something is imported as.
For more information on what as
is capable of, see the Reference