¶ 整型转字节数组
小端序：i16::to_le_bytes
大端序：i16::to_be_bytes
¶ 字节数组转整型
小端序：i16::from_le_bytes
大端序：i16::from_be_bytes
¶ 例子
fn main() {
let bytes: [u8; 2] = [1, 2];
assert_eq!(i16::from_le_bytes(bytes), (2 << 8) + 1);
assert_eq!(i16::from_be_bytes(bytes), (1 << 8) + 2);
let x: i16 = (2 << 8) + 1;
assert_eq!([1, 2], x.to_le_bytes());
assert_eq!([2, 1], x.to_be_bytes());
}