primitive_types4 solution

exercises/04_primitive_types/primitive_types3.rs

@@ -1,5 +1,5 @@
 fn main() {
-    // TODO: Create an array with at least 100 elements in it where the ??? is.
+    // TODO: Create an array called `a` with at least 100 elements in it.
     // let a = ???
 
     if a.len() >= 100 {

exercises/04_primitive_types/primitive_types4.rs

@@ -1,18 +1,15 @@
-// Get a slice out of Array a where the ??? is so that the test passes.
-
 fn main() {
     // You can optionally experiment here.
 }
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-
     #[test]
     fn slice_out_of_array() {
         let a = [1, 2, 3, 4, 5];
 
-        let nice_slice = ???
+        // TODO: Get a slice called `nice_slice` out of the array `a` so that the test passes.
+        // let nice_slice = ???
 
         assert_eq!([2, 3, 4], nice_slice);
     }

rustlings-macros/info.toml

@@ -267,8 +267,8 @@ dir = "04_primitive_types"
 hint = """
 Take a look at the 'Understanding Ownership -> Slices -> Other Slices' section
 of the book: https://doc.rust-lang.org/book/ch04-03-slices.html and use the
-starting and ending (plus one) indices of the items in the `Array` that you
+starting and ending (plus one) indices of the items in the array that you want
-want to end up in the slice.
+to end up in the slice.
 
 If you're curious why the first argument of `assert_eq!` does not have an
 ampersand for a reference since the second argument is a reference, take a look

solutions/04_primitive_types/primitive_types4.rs

@@ -1 +1,23 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+fn main() {
+    // 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);
+    }
+}