options exercise solutions

exercises/12_options/options1.rs

@@ -3,7 +3,6 @@
 // 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.
 // If it's before 10PM, there's 5 scoops left. At 10PM, someone eats it
@@ -13,7 +12,14 @@ fn maybe_icecream(time_of_day: u16) -> Option<u16> {
     // value of 0. The Option output should gracefully handle cases where
     // time_of_day > 23.
     // TODO: Complete the function body - remember to return an Option!
-    ???
+    if time_of_day < 22 {
+        Some(5)
+    } else if time_of_day == 22 || time_of_day <= 23 {
+        Some(0)
+    }
+    else {
+        None
+    }
 }
 
 #[cfg(test)]
@@ -35,6 +41,9 @@ mod tests {
         // TODO: Fix this test. How do you get at the value contained in the
         // Option?
         let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
+        assert_eq!(icecreams.unwrap(), 5);
+        // if let Some(no) = icecreams {
+        //     assert_eq!(no, 5);
+        // }
     }
 }

exercises/12_options/options2.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint options2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[cfg(test)]
 mod tests {
     #[test]
@@ -13,7 +11,7 @@ mod tests {
         let optional_target = Some(target);
 
         // TODO: Make this an if let statement whose value is "Some" type
-        word = optional_target {
+        if let Some(word) = optional_target {
             assert_eq!(word, target);
         }
     }
@@ -29,10 +27,9 @@ mod tests {
 
         let mut cursor = range;
 
-        // TODO: make this a while let statement - remember that vector.pop also
-        // adds another layer of Option<T>. You can stack `Option<T>`s into
-        // while let and if let.
-        integer = optional_integers.pop() {
+        // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>. You can stack `Option<T>`s into while let and if let.
+
+        while let Some(Some(integer)) = optional_integers.pop() {
             assert_eq!(integer, cursor);
             cursor -= 1;
         }

exercises/12_options/options3.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint options3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 struct Point {
     x: i32,
     y: i32,
@@ -14,7 +12,7 @@ fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
     match y {
-        Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
+        Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => panic!("no match!"),
     }
     y; // Fix without deleting this line.