coding rust 14-16

exercises/14_generics/generics1.rs

@@ -6,7 +6,7 @@ fn main() {
     // TODO: Fix the compiler error by annotating the type of the vector
     // `Vec<T>`. Choose `T` as some integer type that can be created from
     // `u8` and `i8`.
-    let mut numbers = Vec::new();
+    let mut numbers: Vec<i16> = Vec::new();
 
     // Don't change the lines below.
     let n1: u8 = 42;

exercises/14_generics/generics2.rs

@@ -1,12 +1,12 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // TODO: Rewrite it using a generic so that it supports wrapping ANY type.
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
 
 // TODO: Adapt the struct's implementation to be generic over the wrapped value.
-impl Wrapper {
-    fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    fn new(value: T) -> Self {
         Wrapper { value }
     }
 }

exercises/15_traits/traits1.rs

@@ -6,6 +6,9 @@ trait AppendBar {
 
 impl AppendBar for String {
     // TODO: Implement `AppendBar` for the type `String`.
+    fn append_bar(self) -> Self {
+        self + "Bar"
+    }
 }
 
 fn main() {

exercises/15_traits/traits2.rs

@@ -4,6 +4,13 @@ trait AppendBar {
 
 // TODO: Implement the trait `AppendBar` for a vector of strings.
 // `append_bar` should push the string "Bar" into the vector.
+impl AppendBar for Vec<String> {
+    fn append_bar(self) -> Self {
+        let mut vec = self.clone();
+        vec.push(String::from("Bar"));
+        vec
+    }
+}
 
 fn main() {
     // You can optionally experiment here.

exercises/15_traits/traits3.rs

@@ -5,7 +5,9 @@ trait Licensed {
     // implementors like the two structs below can share that default behavior
     // without repeating the function.
     // The default license information should be the string "Default license".
-    fn licensing_info(&self) -> String;
+    fn licensing_info(&self) -> String {
+        String::from("Default license")
+    }
 }
 
 struct SomeSoftware {

exercises/15_traits/traits4.rs

@@ -11,7 +11,7 @@ impl Licensed for SomeSoftware {}
 impl Licensed for OtherSoftware {}
 
 // TODO: Fix the compiler error by only changing the signature of this function.
-fn compare_license_types(software1: ???, software2: ???) -> bool {
+fn compare_license_types(software1: impl Licensed, software2: impl Licensed) -> bool {
     software1.licensing_info() == software2.licensing_info()
 }
 

exercises/15_traits/traits5.rs

@@ -19,7 +19,7 @@ impl SomeTrait for OtherStruct {}
 impl OtherTrait for OtherStruct {}
 
 // TODO: Fix the compiler error by only changing the signature of this function.
-fn some_func(item: ???) -> bool {
+fn some_func(item: impl SomeTrait + OtherTrait) -> bool {
     item.some_function() && item.other_function()
 }
 

exercises/16_lifetimes/lifetimes1.rs

@@ -4,7 +4,7 @@
 // not own their own data. What if their owner goes out of scope?
 
 // TODO: Fix the compiler error by updating the function signature.
-fn longest(x: &str, y: &str) -> &str {
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x
     } else {

exercises/16_lifetimes/lifetimes2.rs

@@ -15,6 +15,6 @@ fn main() {
     {
         let string2 = String::from("xyz");
         result = longest(&string1, &string2);
+        println!("The longest string is '{result}'");
     }
-    println!("The longest string is '{result}'");
 }

exercises/16_lifetimes/lifetimes3.rs

@@ -1,9 +1,9 @@
 // Lifetimes are also needed when structs hold references.
 
 // TODO: Fix the compiler errors about the struct.
-struct Book {
-    author: &str,
-    title: &str,
+struct Book<'a> {
+    author: &'a str,
+    title: &'a str,
 }
 
 fn main() {

exercises/quizzes/quiz3.rs

@@ -12,14 +12,14 @@
 // block to support alphabetical report cards in addition to numerical ones.
 
 // TODO: Adjust the struct as described above.
-struct ReportCard {
-    grade: f32,
+struct ReportCard<T> {
+    grade: T,
     student_name: String,
     student_age: u8,
 }
 
 // TODO: Adjust the impl block as described above.
-impl ReportCard {
+impl<T: std::fmt::Display> ReportCard<T> {
     fn print(&self) -> String {
         format!(
             "{} ({}) - achieved a grade of {}",