解答

  2. #![allow(dead_code)]
  3. pub struct User {
  4.     name: String,
  5.     age: u32,
  6.     height: f32,
  7.     visit_count: usize,
  8.     last_blood_pressure: Option<(u32, u32)>,
  9. }
  11. pub struct Measurements {
  12.     height: f32,
  13.     blood_pressure: (u32, u32),
  14. }
  16. pub struct HealthReport<'a> {
  17.     patient_name: &'a str,
  18.     visit_count: u32,
  19.     height_change: f32,
  20.     blood_pressure_change: Option<(i32, i32)>,
  21. }
  23. impl User {
  24.     pub fn new(name: String, age: u32, height: f32) -> Self {
  25.         Self { name, age, height, visit_count: 0, last_blood_pressure: None }
  26.     }
  28.     pub fn visit_doctor(&mut self, measurements: Measurements) -> HealthReport {
  29.         self.visit_count += 1;
  30.         let bp = measurements.blood_pressure;
  31.         let report = HealthReport {
  32.             patient_name: &self.name,
  33.             visit_count: self.visit_count as u32,
  34.             height_change: measurements.height - self.height,
  35.             blood_pressure_change: match self.last_blood_pressure {
  36.                 Some(lbp) => {
  37.                     Some((bp.0 as i32 - lbp.0 as i32, bp.1 as i32 - lbp.1 as i32))
  38.                 }
  39.                 None => None,
  40.             },
  41.         };
  42.         self.height = measurements.height;
  43.         self.last_blood_pressure = Some(bp);
  44.         report
  45.     }
  46. }
  48. fn main() {
  49.     let bob = User::new(String::from("Bob"), 32, 155.2);
  50.     println!("I'm {} and my age is {}", bob.name, bob.age);
  51. }
  53. #[test]
  54. fn test_visit() {
  55.     let mut bob = User::new(String::from("Bob"), 32, 155.2);
  56.     assert_eq!(bob.visit_count, 0);
  57.     let report =
  58.         bob.visit_doctor(Measurements { height: 156.1, blood_pressure: (120, 80) });
  59.     assert_eq!(report.patient_name, "Bob");
  60.     assert_eq!(report.visit_count, 1);
  61.     assert_eq!(report.blood_pressure_change, None);
  63.     let report =
  64.         bob.visit_doctor(Measurements { height: 156.1, blood_pressure: (115, 76) });
  66.     assert_eq!(report.visit_count, 2);
  67.     assert_eq!(report.blood_pressure_change, Some((-5, -4)));
  68. }