cr0wbar's Rust course - Pattern matching: quiz

Question 1

Why does the following code not compile?

fn main() {
let string = ":)";
match string {
  ":)" => {
   println!("Happy!")
  }
  ":(" => {
   println!("Sad!")
  }
  ":|" => {
   println!("Meh...")
  }
}
}

The match statement is missing a wildcard branch
The branches of the match statement are missing ranges
The println!() statements are missing semicolons

Question 2

True or false:

It is impossible to exhaustively match on enum variants/discriminants without a wildcard branch.

True False

Question 3

What is the printed output of the following?

enum Structs {
SplitString { fst: String, snd: String },
}

fn main() {
let strs = Structs::SplitString {
  fst: String::from("hel"),
  snd: String::from("lo!")
};
if let Structs::SplitString {
  fst: first,
  snd: second
} = strs {
  println!("{}{}", first, second)
}
}

Output:

Question 4

Fill in the blank for the match statement below such that all 32-bit negative numbers are included.
(Think back to the error examples given for match statements!)

fn mtch(a: i32) {
match a {
   => { println!("Small!") }
  0 => { println!("Just right!") }

  1.. => { println!("Big!") }

}
}

Question 5

Will the following code compile?

enum Structs {
ThreeDimensions {
  x: i32,
  y: i32,
  z: i32
},
Precise3D {
  x: f32,
  y: f32,
  z: f32
}
}

fn main() {
let int_point = Structs::ThreeDimensions {
  x: 27,
  y: 68,
  z: 91
};
let float_point = Structs::Precise3D {
  x: 23.456,
  y: 75.364,
  z: 21.052
};
if let (Structs::ThreeDimensions { x: 27, .. },
  Structs::Precise3D { z: 21.035, .. }) =
  (int_point, float_point) {
   println!("Match!")
  } else {
   println!("Mismatch!")
  }
}

Yes No

Quiz

Have you met your match?

Question 1

Question 2

Question 3

Question 4

Question 5