HashMap

[learn-rust.git] / src / main.rs

diff --git a/src/main.rs b/src/main.rs
index 058f8584cf31063cdef5dc9cd61a9daf38bfce00..ff65a0611a6e7b40a0a86501a239ab657cc4156a 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,11 @@
 mod word_utils;
 
+use std::collections::HashMap;
+
 use word_utils::{first_word, second_word};
 
 fn main() {
+    // strings and functions
     let s = String::from("Hello world");
     println!("first word: '{}'", first_word(&s));
     println!("second word: '{}'", second_word(&s).unwrap());
@@ -14,4 +17,51 @@ fn main() {
         Some(w) => println!("match: second word of '{}' exists: {}", s2, w),
         None => println!("match: second word of '{}' does not exist", s2),
     }
+
+    // vectors
+    let v1 = vec![1, 2, 3];
+    println!("statically initialized vector: {:?}", v1);
+
+    let mut v2: Vec<String> = Vec::new();
+    v2.push("Hello".to_string());
+    v2.push(String::from("world"));
+    println!("dynamically built vector: {:?}", v2);
+    println!("first element: {}", v2[0]);
+    for el in &mut v2 {
+        *el += "xx";
+    }
+    for el in &v2 {
+        println!("{}", el);
+    }
+
+    // hash maps
+    let mut scores = HashMap::new();
+    scores.insert("john", 10);
+    scores.insert("mary", 20);
+
+    println!("scores: {:?}", scores);
+
+    // hash map with .collect()
+    let persons = vec![("homer", 42), ("marge", 30)];
+    let collect_scores: HashMap<_, _> = persons.into_iter().collect();
+    println!("collect_scores: {:?}", collect_scores);
+
+    for (p, s) in &collect_scores {
+        println!("person {}: score {}", p, s);
+    }
+
+    println!("john's score: {}", scores.get("john").unwrap());
+    println!("jake's score: {}", scores.get("jake").unwrap_or(&-1));
+
+    // double scores
+    for (_, v) in scores.iter_mut() {
+        *v *= 2;
+    }
+    println!("scores after doubling: {:?}", scores);
+
+    // double scores of immutable hashmap (rebuild it)
+    let collect_scores: HashMap<_, _> = collect_scores.iter()
+        .map(|(k, v)| (k, 2 * v))
+        .collect();
+    println!("collect_scores after rebuilding with doubling: {:?}", collect_scores);
 }