slice

13-slice/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "slice"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

13-slice/src/main.rs

@@ -0,0 +1,42 @@
+fn main() 
+    {
+        println!("Hello, world!");
+        
+        //mutable because we will clean it later.
+            let mut s = String::from("Yellow Duck");
+        //it's not &String, it's literal thanks to slice
+            let firts = firts_world(&s[..]);
+        println!("{}", firts);
+        s.clear();
+        //s.clear function has mutable reference to truncate
+        //and if we print "first" after this
+        //we have to have mutable and immutable references
+        //at the same time
+        //it's forbidden as we've learned before
+            //println!("{}", firts);
+
+        let a = [0,1,2,3,4,5];
+        let b = &a[2..4];
+        println!("{}-{}", b[0], b[1]);
+    }
+
+fn firts_world(s: &str) -> &str
+    {   
+        //it converts string to byte array
+            let bytes = s.as_bytes();
+
+        //iter is iteration we will learn later, even i don't know well
+        //enumerate returns index and reference in order as a tuple
+            for(i, &item) in bytes.iter().enumerate()
+                {
+                    //We're trying to catch "space" to sepeterate our string
+                    //Book says also we will learn pattern matching later
+                        if item == b' '
+                            {
+                                //when we find "space", we return first slice
+                                    return &s[0..i];
+                            }
+                }
+        //If we can not find any space, we return whole string as a literal
+            &s[..]
+    }