finish chapter 5

3 files changed, 58 insertions, 0 deletions

diff --git a/rust/theBook/chapter-4-understanding-ownership/emp1.rs b/rust/theBook/chapter-4-understanding-ownership/emp1.rs
new file mode 100644
index 0000000..a0f4bbd
--- /dev/null
+++ b/rust/theBook/chapter-4-understanding-ownership/emp1.rs
@@ -0,0 +1,9 @@
+fn main() {
+    let mut s = String::from("hello");
+
+    let r1 = &s;
+    let r2 = &s;
+    println!("{},{}",r1,r2);
+    let r3 = &mut s;
+    println!("{r3}");
+}
diff --git a/rust/theBook/chapter-4-understanding-ownership/emp2.rs b/rust/theBook/chapter-4-understanding-ownership/emp2.rs
new file mode 100644
index 0000000..02a24b0
--- /dev/null
+++ b/rust/theBook/chapter-4-understanding-ownership/emp2.rs
@@ -0,0 +1,11 @@
+fn main() {
+    let str = dangle();
+
+    println!("{str}");
+}
+
+fn dangle() -> &String {
+    let s = String::from("Hello");
+
+    &s
+}
diff --git a/rust/theBook/chapter-4-understanding-ownership/str.rs b/rust/theBook/chapter-4-understanding-ownership/str.rs
new file mode 100644
index 0000000..09bab67
--- /dev/null
+++ b/rust/theBook/chapter-4-understanding-ownership/str.rs
@@ -0,0 +1,38 @@
+fn first_word(s: &String) -> usize {
+    let bytes = s.as_bytes();
+
+    for (i, &item) in bytes.iter().enumerate() {
+        if item == b' ' {
+            return i;
+        }
+    }
+
+    s.len()
+}
+
+fn second_word(s: &str) -> &str {
+    let bytes = s.as_bytes();
+
+    for (i, &item) in bytes.iter().enumerate() {
+        if item == b' ' {
+            return &s[0..i];
+        }
+    }
+
+    &s[0..s.len()]
+}
+
+fn main() {
+    let mut s = String::from("hello world");
+
+    let word = first_word(&s);
+
+    println!("{word}");
+
+    println!("{}",&s[0..5]);
+
+    let word2 = second_word(&s[..]);
+
+    println!("{}",&word2);
+    s.clear();
+}