primitive_types4 solution

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);
+    }
+}