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[Add] exercises/options

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This commit is contained in:
Phan Huy Hoang 2023-01-07 00:21:37 +07:00
parent 170d20a12e
commit ca8416cb0e
3 changed files with 10 additions and 19 deletions
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14
exercises/options/options1.rs
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@ -1,16 +1,15 @@
// options1.rs // options1.rs
// Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
// This function returns how much icecream there is left in the fridge. // This function returns how much icecream there is left in the fridge.
// If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
// all, so there'll be no more left :( // all, so there'll be no more left :(
fn maybe_icecream(time_of_day: u16) -> Option<u16> { fn maybe_icecream(time_of_day: u16) -> Option<u16> {
// We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a value of 0 match time_of_day {
// The Option output should gracefully handle cases where time_of_day > 23. 0..=21 => Some(5),
// TODO: Complete the function body - remember to return an Option! 22..=23 => Some(0),
??? _ => None
}
} }
#[cfg(test)] #[cfg(test)]
@ -28,8 +27,7 @@ mod tests {
#[test] #[test]
fn raw_value() { fn raw_value() {
// TODO: Fix this test. How do you get at the value contained in the Option? let icecreams = maybe_icecream(12).unwrap();
let icecreams = maybe_icecream(12);
assert_eq!(icecreams, 5); assert_eq!(icecreams, 5);
} }
} }

11
exercises/options/options2.rs
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@ -1,8 +1,6 @@
// options2.rs // options2.rs
// Execute `rustlings hint options2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint options2` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
#[cfg(test)] #[cfg(test)]
mod tests { mod tests {
use super::*; use super::*;
@ -12,8 +10,7 @@ mod tests {
let target = "rustlings"; let target = "rustlings";
let optional_target = Some(target); let optional_target = Some(target);
// TODO: Make this an if let statement whose value is "Some" type if let Some(word) = optional_target {
word = optional_target {
assert_eq!(word, target); assert_eq!(word, target);
} }
} }
@ -26,10 +23,8 @@ mod tests {
optional_integers.push(Some(i)); optional_integers.push(Some(i));
} }
// TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T> while let Some(integer) = optional_integers.pop() {
// You can stack `Option<T>`'s into while let and if let assert_eq!(integer, Some(range));
integer = optional_integers.pop() {
assert_eq!(integer, range);
range -= 1; range -= 1;
} }
} }

4
exercises/options/options3.rs
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@ -1,8 +1,6 @@
// options3.rs // options3.rs
// Execute `rustlings hint options3` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint options3` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
struct Point { struct Point {
x: i32, x: i32,
y: i32, y: i32,
@ -12,7 +10,7 @@ fn main() {
let y: Option<Point> = Some(Point { x: 100, y: 200 }); let y: Option<Point> = Some(Point { x: 100, y: 200 });
match y { match y {
Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y), Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
_ => println!("no match"), _ => println!("no match"),
} }
y; // Fix without deleting this line. y; // Fix without deleting this line.