Improve naming in std types exercise

src/std-types/exercise.md

@@ -15,7 +15,7 @@ It uses a
 to keep track of what values have been seen and how many times each one has
 appeared.
 
-The initial version of `Counter` is hardcoded to only work for `u32` values.
+The initial version of `Counter` is hardcoded to only work for `char` values.
 Make the struct and its methods generic over the type of value being tracked,
 that way `Counter` can track any type of value.
 
@@ -32,29 +32,29 @@ use std::collections::HashMap;
 
 /// Counter counts the number of times each value of type T has been seen.
 struct Counter {
-    values: HashMap<u32, u64>,
+    counts: HashMap<char, u64>,
 }
 
 impl Counter {
     /// Create a new Counter.
     fn new() -> Self {
         Counter {
-            values: HashMap::new(),
+            counts: HashMap::new(),
         }
     }
 
     /// Count an occurrence of the given value.
-    fn count(&mut self, value: u32) {
-        if self.values.contains_key(&value) {
-            *self.values.get_mut(&value).unwrap() += 1;
+    fn count(&mut self, value: char) {
+        if self.counts.contains_key(&value) {
+            *self.counts.get_mut(&value).unwrap() += 1;
         } else {
-            self.values.insert(value, 1);
+            self.counts.insert(value, 1);
         }
     }
 
     /// Return the number of times the given value has been seen.
-    fn times_seen(&self, value: u32) -> u64 {
-        self.values.get(&value).copied().unwrap_or_default()
+    fn times_seen(&self, value: char) -> u64 {
+        self.counts.get(&value).copied().unwrap_or_default()
     }
 }
 

src/std-types/exercise.rs

@@ -20,38 +20,48 @@ use std::hash::Hash;
 
 /// Counter counts the number of times each value of type T has been seen.
 struct Counter<T> {
-    values: HashMap<T, u64>,
+    counts: HashMap<T, u64>,
 }
 
 impl<T: Eq + Hash> Counter<T> {
     /// Create a new Counter.
     fn new() -> Self {
-        Counter { values: HashMap::new() }
+        Counter { counts: HashMap::new() }
     }
 
     /// Count an occurrence of the given value.
-    fn count(&mut self, value: T) {
-        *self.values.entry(value).or_default() += 1;
+    fn count(&mut self, item: T) {
+        *self.counts.entry(item).or_default() += 1;
     }
 
     /// Return the number of times the given value has been seen.
-    fn times_seen(&self, value: T) -> u64 {
-        self.values.get(&value).copied().unwrap_or_default()
+    fn times_seen(&self, item: T) -> u64 {
+        self.counts.get(&item).copied().unwrap_or_default()
     }
 }
 
 // ANCHOR: main
 fn main() {
-    let mut ctr = Counter::new();
-    ctr.count(13);
-    ctr.count(14);
-    ctr.count(16);
-    ctr.count(14);
-    ctr.count(14);
-    ctr.count(11);
+    let mut charctr = Counter::new();
+    charctr.count(' ');
+    charctr.count('a');
+    charctr.count('¥');
+    charctr.count('a');
+    println!(
+        "most common character: {:?}",
+        charctr.counts.keys().max_by_key(|&c| charctr.times_seen(*c))
+    );
+
+    let mut intctr = Counter::new();
+    intctr.count(13);
+    intctr.count(14);
+    intctr.count(16);
+    intctr.count(14);
+    intctr.count(14);
+    intctr.count(11);
 
     for i in 10..20 {
-        println!("saw {} values equal to {}", ctr.times_seen(i), i);
+        println!("saw {} values equal to {}", intctr.times_seen(i), i);
     }
 
     let mut strctr = Counter::new();