Complete move semantics exercises

exercises/06_move_semantics/move_semantics1.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
@@ -15,7 +13,7 @@ fn main() {
 }
 
 fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let vec = vec;
+    let mut vec = vec;
 
     vec.push(88);
 

exercises/06_move_semantics/move_semantics2.rs

@@ -5,13 +5,20 @@
 // Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
 
-    let mut vec1 = fill_vec(vec0);
+    let vec1 = fill_vec(vec0.clone());
+
+    // When vec0 is passed to fill_vec, the function takes OWNERSHIP 
+    // of the vector. It mutates the vector and passes ownershpip to vec1. 
+    // Once a value has moved, we can no longer use it. 
+    // this is why, we need to clone it so that we can use it again
+
+    // Using clone() makes an entire copy of the vector. DEEP COPY. 
+    // It is also a separate object in memory. 
+    // Changes to the original vector does not affect the cloned vector and vice versa
 
     assert_eq!(vec0, vec![22, 44, 66]);
     assert_eq!(vec1, vec![22, 44, 66, 88]); 

exercises/06_move_semantics/move_semantics3.rs

@@ -6,8 +6,6 @@
 // Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
@@ -17,7 +15,7 @@ fn main() {
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
     vec.push(88);
 
     vec

exercises/06_move_semantics/move_semantics4.rs

@@ -7,13 +7,11 @@
 // Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
 fn main() {
     let vec0 = vec![22, 44, 66];
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     assert_eq!(vec1, vec![22, 44, 66, 88]);
 }
@@ -21,8 +19,10 @@ fn main() {
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument - don't change this!
 fn fill_vec() -> Vec<i32> {
     // Instead, let's create and fill the Vec in here - how do you do that?
-    let mut vec = vec;
-
+    let mut vec: Vec<i32> = Vec::new();
+    vec.push(22);
+    vec.push(44);
+    vec.push(66);
     vec.push(88);
 
     vec

exercises/06_move_semantics/move_semantics5.rs

@@ -6,14 +6,30 @@
 // Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 #[test]
+// Adding the curly braces makes the the scope explicit.
+// This is just more readable and clear to people to reading.
 fn main() {
     let mut x = 100;
+     {
         let y = &mut x;
-    let z = &mut x;
         *y += 100;
+     }
+     {
+        let z = &mut x;
         *z += 1000;
+     }
      assert_eq!(x, 1200);
-}
+ }
+
+// fn main() {
+   // let mut x = 100;
+
+    // scopes x and here and then y is out of scope afterwards
+    //let y = &mut x;
+    //*y += 100;
+
+    //let z = &mut x;
+    //*z += 1000;
+    //assert_eq!(x, 1200);
+//}

exercises/06_move_semantics/move_semantics6.rs

@@ -5,24 +5,38 @@
 // Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     let data = "Rust is great!".to_string();
 
-    get_char(data);
+    // get_char is taking ownership of the data
+    // a reference is like a pointer.
+    // it's an address to the data that we want to access.
+    // the difference though is that a reference is guaranteed to point to a valid value
+    // of a particular type for the life of that
+    get_char(&data);
 
-    string_uppercase(&data);
+    string_uppercase(data);
 }
 
 // Should not take ownership
-fn get_char(data: String) -> char {
+
+//In this case, the function is taking a reference to avoid data copying
+// The original string is needed after the function call.
+// get_char does not modify the data, only reads it so we can just pass the reference.
+
+
+fn get_char(data: &String) -> char {
     data.chars().last().unwrap()
+    // This function is getting the last character of the string reference
+    // in this test case, i would be '!'
+    // println!('{}'. char); would print '!'
 }
 
 // Should take ownership
-fn string_uppercase(mut data: &String) {
-    data = &data.to_uppercase();
+// because it is modifying the value of data
+// the mut in the parameters allows it to reassign a value to the 'data'
+fn string_uppercase(mut data: String) {
+    data = data.to_uppercase();
 
     println!("{}", data);
 }