rustlings: complete 00 and 01

17 files changed, 77 insertions, 30 deletions

diff --git a/rustlings/.rustlings-state.txt b/rustlings/.rustlings-state.txt
new file mode 100644
index 0000000..b83f6a3
--- /dev/null
+++ b/rustlings/.rustlings-state.txt
@@ -0,0 +1,12 @@
+DON'T EDIT THIS FILE!
+
+functions1
+
+intro1
+intro2
+variables1
+variables2
+variables3
+variables4
+variables5
+variables6
diff --git a/rustlings/exercises/00_intro/intro1.rs b/rustlings/exercises/00_intro/intro1.rs
index 172a6ab..440ae83 100644
--- a/rustlings/exercises/00_intro/intro1.rs
+++ b/rustlings/exercises/00_intro/intro1.rs
@@ -21,4 +21,8 @@ fn main() {
     println!("The file of this exercise is `exercises/00_intro/intro1.rs`. Have a look!");
     println!("The current exercise path will be always shown under the progress bar.");
     println!("You can click on the path to open the exercise file in your editor.");
+    println!();
+    println!("New line");
+    println!(  "   another line   ");
+    println!(r#"   yet another line"#);
 }
diff --git a/rustlings/exercises/00_intro/intro2.rs b/rustlings/exercises/00_intro/intro2.rs
index c6cb645..e0b5e27 100644
--- a/rustlings/exercises/00_intro/intro2.rs
+++ b/rustlings/exercises/00_intro/intro2.rs
@@ -1,4 +1,3 @@
 fn main() {
-    // TODO: Fix the code to print "Hello world!".
-    printline!("Hello world!");
+    println!("Hello world!");
 }
diff --git a/rustlings/exercises/01_variables/variables1.rs b/rustlings/exercises/01_variables/variables1.rs
index f83b44d..2df7df8 100644
--- a/rustlings/exercises/01_variables/variables1.rs
+++ b/rustlings/exercises/01_variables/variables1.rs
@@ -1,6 +1,5 @@
 fn main() {
-    // TODO: Add the missing keyword.
-    x = 5;
+    let x = 5;
 
     println!("x has the value {x}");
 }
diff --git a/rustlings/exercises/01_variables/variables2.rs b/rustlings/exercises/01_variables/variables2.rs
index e2a3603..b35a0bf 100644
--- a/rustlings/exercises/01_variables/variables2.rs
+++ b/rustlings/exercises/01_variables/variables2.rs
@@ -1,6 +1,5 @@
 fn main() {
-    // TODO: Change the line below to fix the compiler error.
-    let x;
+    let x = 10;
 
     if x == 10 {
         println!("x is ten!");
diff --git a/rustlings/exercises/01_variables/variables3.rs b/rustlings/exercises/01_variables/variables3.rs
index 06f35bb..47b2be4 100644
--- a/rustlings/exercises/01_variables/variables3.rs
+++ b/rustlings/exercises/01_variables/variables3.rs
@@ -1,6 +1,5 @@
 fn main() {
-    // TODO: Change the line below to fix the compiler error.
-    let x: i32;
+    let x = 10;
 
     println!("Number {x}");
 }
diff --git a/rustlings/exercises/01_variables/variables4.rs b/rustlings/exercises/01_variables/variables4.rs
index 6c138b1..d2967ea 100644
--- a/rustlings/exercises/01_variables/variables4.rs
+++ b/rustlings/exercises/01_variables/variables4.rs
@@ -1,6 +1,5 @@
-// TODO: Fix the compiler error.
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {x}");
 
     x = 5; // Don't change this line
diff --git a/rustlings/exercises/01_variables/variables5.rs b/rustlings/exercises/01_variables/variables5.rs
index cf5620d..be94598 100644
--- a/rustlings/exercises/01_variables/variables5.rs
+++ b/rustlings/exercises/01_variables/variables5.rs
@@ -2,7 +2,6 @@ fn main() {
     let number = "T-H-R-E-E"; // Don't change this line
     println!("Spell a number: {number}");
 
-    // TODO: Fix the compiler error by changing the line below without renaming the variable.
-    number = 3;
+    let number = 3;
     println!("Number plus two is: {}", number + 2);
 }
diff --git a/rustlings/exercises/01_variables/variables6.rs b/rustlings/exercises/01_variables/variables6.rs
index 4a040fd..c40e572 100644
--- a/rustlings/exercises/01_variables/variables6.rs
+++ b/rustlings/exercises/01_variables/variables6.rs
@@ -1,5 +1,4 @@
-// TODO: Change the line below to fix the compiler error.
-const NUMBER = 3;
+const NUMBER: i32 = 3;
 
 fn main() {
     println!("Number: {NUMBER}");
diff --git a/rustlings/solutions/00_intro/intro1.rs b/rustlings/solutions/00_intro/intro1.rs
index dcf2377..4fe8454 100644
--- a/rustlings/solutions/00_intro/intro1.rs
+++ b/rustlings/solutions/00_intro/intro1.rs
@@ -1,4 +1,5 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // Congratulations, you finished the first exercise 🎉
+    // As an introduction to Rustlings, the first exercise only required
+    // entering `n` in the terminal to go to the next exercise.
 }
diff --git a/rustlings/solutions/00_intro/intro2.rs b/rustlings/solutions/00_intro/intro2.rs
index dcf2377..b8e031a 100644
--- a/rustlings/solutions/00_intro/intro2.rs
+++ b/rustlings/solutions/00_intro/intro2.rs
@@ -1,4 +1,4 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // `println!` instead of `printline!`.
+    println!("Hello world!");
 }
diff --git a/rustlings/solutions/01_variables/variables1.rs b/rustlings/solutions/01_variables/variables1.rs
index dcf2377..58d046b 100644
--- a/rustlings/solutions/01_variables/variables1.rs
+++ b/rustlings/solutions/01_variables/variables1.rs
@@ -1,4 +1,6 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // Declaring variables requires the `let` keyword.
+    let x = 5;
+
+    println!("x has the value {x}");
 }
diff --git a/rustlings/solutions/01_variables/variables2.rs b/rustlings/solutions/01_variables/variables2.rs
index dcf2377..50b8d1b 100644
--- a/rustlings/solutions/01_variables/variables2.rs
+++ b/rustlings/solutions/01_variables/variables2.rs
@@ -1,4 +1,16 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // The easiest way to fix the compiler error is to initialize the
+    // variable `x`. By setting its value to an integer, Rust infers its type
+    // as `i32` which is the default type for integers.
+    let x = 42;
+
+    // But we can enforce a type different from the default `i32` by adding
+    // a type annotation:
+    // let x: u8 = 42;
+
+    if x == 10 {
+        println!("x is ten!");
+    } else {
+        println!("x is not ten!");
+    }
 }
diff --git a/rustlings/solutions/01_variables/variables3.rs b/rustlings/solutions/01_variables/variables3.rs
index dcf2377..15f6557 100644
--- a/rustlings/solutions/01_variables/variables3.rs
+++ b/rustlings/solutions/01_variables/variables3.rs
@@ -1,4 +1,15 @@
+#![allow(clippy::needless_late_init)]
+
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // Reading uninitialized variables isn't allowed in Rust!
+    // Therefore, we need to assign a value first.
+    let x: i32 = 42;
+
+    println!("Number {x}");
+
+    // It is possible to declare a variable and initialize it later.
+    // But it can't be used before initialization.
+    let y: i32;
+    y = 42;
+    println!("Number {y}");
 }
diff --git a/rustlings/solutions/01_variables/variables4.rs b/rustlings/solutions/01_variables/variables4.rs
index dcf2377..7de6bcb 100644
--- a/rustlings/solutions/01_variables/variables4.rs
+++ b/rustlings/solutions/01_variables/variables4.rs
@@ -1,4 +1,9 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // In Rust, variables are immutable by default.
+    // Adding the `mut` keyword after `let` makes the declared variable mutable.
+    let mut x = 3;
+    println!("Number {x}");
+
+    x = 5;
+    println!("Number {x}");
 }
diff --git a/rustlings/solutions/01_variables/variables5.rs b/rustlings/solutions/01_variables/variables5.rs
index dcf2377..0ea3903 100644
--- a/rustlings/solutions/01_variables/variables5.rs
+++ b/rustlings/solutions/01_variables/variables5.rs
@@ -1,4 +1,9 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    let number = "T-H-R-E-E";
+    println!("Spell a number: {number}");
+
+    // Using variable shadowing
+    // https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
+    let number = 3;
+    println!("Number plus two is: {}", number + 2);
 }
diff --git a/rustlings/solutions/01_variables/variables6.rs b/rustlings/solutions/01_variables/variables6.rs
index dcf2377..25b7a1e 100644
--- a/rustlings/solutions/01_variables/variables6.rs
+++ b/rustlings/solutions/01_variables/variables6.rs
@@ -1,4 +1,6 @@
+// The type of constants must always be annotated.
+const NUMBER: u64 = 3;
+
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    println!("Number: {NUMBER}");
 }