strings4 solution

solutions/09_strings/strings4.rs

@@ -1 +1,38 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+fn string_slice(arg: &str) {
+    println!("{arg}");
+}
+fn string(arg: String) {
+    println!("{arg}");
+}
+
+fn main() {
+    string_slice("blue");
+
+    string("red".to_string());
+
+    string(String::from("hi"));
+
+    string("rust is fun!".to_owned());
+
+    // Here, both answers work.
+    // `.into()` converts a type into an expected type.
+    // If it is called where `String` is expected, it will convert `&str` to `String`.
+    // But if is called where `&str` is expected, then `&str` is kept `&str` since no
+    // conversion is needed.
+    string("nice weather".into());
+    string_slice("nice weather".into());
+    //                         ^^^^^^^ the compiler recommends removing the `.into()`
+    //                                 call because it is a useless conversion.
+
+    string(format!("Interpolation {}", "Station"));
+
+    // WARNING: This is byte indexing, not character indexing.
+    // Character indexing can be done using `s.chars().nth(INDEX)`.
+    string_slice(&String::from("abc")[0..1]);
+
+    string_slice("  hello there ".trim());
+
+    string("Happy Monday!".replace("Mon", "Tues"));
+
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
+}