我正在努力学习Rust，我一直在思考char的宽度是4字节.我可以将char转换为u32，结果很好(它们都是4字节宽)，然而，当我将u32转换为char时，Rust抱怨:
fn main() {
let pizza_hex: u32 = 0x1f355;
let pizza: char = '?'; // (pizza char: http://www.fileformat.info/info/unicode/char/1f355/index.htm)
// pizza as hex = 1f355
println!("pizza as hex = {:x}", pizza as u32);
// size of pizza = 4
println!("size of pizza = {}", std::mem::size_of_val(&pizza));
// This doesn't work super well
println!("{} == {}", pizza_hex as char, pizza);
}
error[E0604]: only `u8` can be cast as `char`, not `u32`
--> src/main.rs:12:26
|
12 | println!("{} == {}", pizza_hex as char, pizza);
| ^^^^^^^^^^^^^^^^^
知道为什么吗？