From 8f0234e3a297d99c958e8b85e131ec9323cd53c7 Mon Sep 17 00:00:00 2001
From: Hunter Kvalevog <hunter@kvog.sh>
Date: Fri, 18 Sep 2026 16:30:30 -0500
Subject: rustlings: complete 04

---
 .../04_primitive_types/primitive_types1.rs         | 11 +++++++++--
 .../04_primitive_types/primitive_types2.rs         | 21 ++++++++++++++++++--
 .../04_primitive_types/primitive_types3.rs         | 11 +++++++++--
 .../04_primitive_types/primitive_types4.rs         | 23 ++++++++++++++++++++--
 .../04_primitive_types/primitive_types5.rs         |  8 ++++++--
 .../04_primitive_types/primitive_types6.rs         | 16 +++++++++++++--
 6 files changed, 78 insertions(+), 12 deletions(-)

(limited to 'rustlings/solutions')

diff --git a/rustlings/solutions/04_primitive_types/primitive_types1.rs b/rustlings/solutions/04_primitive_types/primitive_types1.rs
index dcf2377..fac6ec0 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types1.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types1.rs
@@ -1,4 +1,11 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    let is_morning = true;
+    if is_morning {
+        println!("Good morning!");
+    }
+
+    let is_evening = !is_morning;
+    if is_evening {
+        println!("Good evening!");
+    }
 }
diff --git a/rustlings/solutions/04_primitive_types/primitive_types2.rs b/rustlings/solutions/04_primitive_types/primitive_types2.rs
index dcf2377..eecc680 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types2.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types2.rs
@@ -1,4 +1,21 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    let my_first_initial = 'C';
+    if my_first_initial.is_alphabetic() {
+        println!("Alphabetical!");
+    } else if my_first_initial.is_numeric() {
+        println!("Numerical!");
+    } else {
+        println!("Neither alphabetic nor numeric!");
+    }
+
+    // Example with an emoji.
+    let your_character = '🦀';
+
+    if your_character.is_alphabetic() {
+        println!("Alphabetical!");
+    } else if your_character.is_numeric() {
+        println!("Numerical!");
+    } else {
+        println!("Neither alphabetic nor numeric!");
+    }
 }
diff --git a/rustlings/solutions/04_primitive_types/primitive_types3.rs b/rustlings/solutions/04_primitive_types/primitive_types3.rs
index dcf2377..8dd109f 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types3.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types3.rs
@@ -1,4 +1,11 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // An array with 100 elements of the value 42.
+    let a = [42; 100];
+
+    if a.len() >= 100 {
+        println!("Wow, that's a big array!");
+    } else {
+        println!("Meh, I eat arrays like that for breakfast.");
+        panic!("Array not big enough, more elements needed");
+    }
 }
diff --git a/rustlings/solutions/04_primitive_types/primitive_types4.rs b/rustlings/solutions/04_primitive_types/primitive_types4.rs
index dcf2377..4807e66 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types4.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types4.rs
@@ -1,4 +1,23 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn slice_out_of_array() {
+        let a = [1, 2, 3, 4, 5];
+        //       0  1  2  3  4  <- indices
+        //          -------
+        //             |
+        //             +--- slice
+
+        // Note that the upper index 4 is excluded.
+        let nice_slice = &a[1..4];
+        assert_eq!([2, 3, 4], nice_slice);
+
+        // The upper index can be included by using the syntax `..=` (with `=` sign)
+        let nice_slice = &a[1..=3];
+        assert_eq!([2, 3, 4], nice_slice);
+    }
 }
diff --git a/rustlings/solutions/04_primitive_types/primitive_types5.rs b/rustlings/solutions/04_primitive_types/primitive_types5.rs
index dcf2377..46d7ae8 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types5.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types5.rs
@@ -1,4 +1,8 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    let cat = ("Furry McFurson", 3.5);
+
+    // Destructuring the tuple.
+    let (name, age) = cat;
+
+    println!("{name} is {age} years old");
 }
diff --git a/rustlings/solutions/04_primitive_types/primitive_types6.rs b/rustlings/solutions/04_primitive_types/primitive_types6.rs
index dcf2377..9b7c277 100644
--- a/rustlings/solutions/04_primitive_types/primitive_types6.rs
+++ b/rustlings/solutions/04_primitive_types/primitive_types6.rs
@@ -1,4 +1,16 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn indexing_tuple() {
+        let numbers = (1, 2, 3);
+
+        // Tuple indexing syntax.
+        let second = numbers.1;
+
+        assert_eq!(second, 2, "This is not the 2nd number in the tuple!");
+    }
 }
-- 
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