Adds part02 with enum and pattern matching

codes/rust_lang/part01/src/main.rs

@@ -2,6 +2,7 @@
 ///     - Functions
 ///     - Arguments are "moved"
 ///     - if is an expression
+///     - for loops revisited
 ///     - Tuples
 ///     - Destructuring
 
@@ -20,10 +21,9 @@ fn check_size(size: usize) {
 
 // Prints tab and returns tab.
 // Tab would be destructed at the end of the function otherwise.
-fn print_tab(tab: [i32; SIZE], size: usize) -> [i32; SIZE] {
-    check_size(size);
-    for i in 0..size {
-        print!("{} ", tab[i]);
+fn print_tab(tab: [i32; SIZE]) -> [i32; SIZE] {
+    for t in tab {
+        print!("{} ", t);
     }
     println!();
     tab
@@ -39,9 +39,9 @@ fn min_i32(lhs: i32, rhs: i32) -> i32 {
 
 fn find_min(tab: [i32; SIZE], size: usize) -> ([i32; SIZE], i32) {
     check_size(size);
-    let mut min = tab[0];
-    for i in 1..size {
-        min = min_i32(min, tab[i]);
+    let mut min = i32::MAX;
+    for t in tab {
+        min = min_i32(min, t);
     }
     (tab, min)
 }
@@ -50,7 +50,7 @@ fn main() {
     let tab = read_command_line();
 
     println!("Among the numbers in the list:");
-    let tab = print_tab(tab, SIZE);
+    let tab = print_tab(tab);
 
     // There are alternatives to access fields of tuples
     let (_, min) = find_min(tab, SIZE);

codes/rust_lang/part02/Cargo.toml

+[package]
+name = "part02"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

codes/rust_lang/part02/src/main.rs

+/// In part03 we introduce `Enums` (also known as `Algebraic Data Types`), `Pattern Matching`,
+/// and `Static Functions`.
+
+enum NumberOrNothing {
+    Nothing,
+    Number(i32),
+}
+
+impl NumberOrNothing {
+    fn new(val: i32) -> Self {
+        NumberOrNothing::Number(val)
+    }
+
+    // Static function
+    fn print(self) {
+        match self {
+            NumberOrNothing::Nothing => println!("No number."),
+            NumberOrNothing::Number(val) => println!("The number is: {}", val),
+        }
+    }
+}
+
+const SIZE: usize = 9;
+
+fn read_command_line() -> [i32; SIZE] {
+    [10, 32, 12, 43, 52, 53, 83, 2, 9]
+}
+
+// Prints tab and returns tab.
+// Tab would be destructed at the end of the function otherwise.
+fn print_tab(tab: [i32; SIZE]) -> [i32; SIZE] {
+    for t in tab {
+        print!("{} ", t);
+    }
+    println!();
+    tab
+}
+
+fn min_i32(lhs: i32, rhs: i32) -> i32 {
+    if lhs < rhs {
+        lhs
+    } else {
+        rhs
+    }
+}
+
+fn find_min(tab: [i32; SIZE]) -> ([i32; SIZE], NumberOrNothing) {
+    let mut min = NumberOrNothing::Nothing;
+    for t in tab {
+        match min {
+            NumberOrNothing::Nothing => min = NumberOrNothing::new(t),
+            NumberOrNothing::Number(val) => min = NumberOrNothing::new(min_i32(val, t)),
+        }
+    }
+    (tab, min)
+}
+
+fn main() {
+    let tab = read_command_line();
+
+    println!("Among the numbers in the list:");
+    let tab = print_tab(tab);
+
+    // There are alternatives to access fields of tuples
+    let (_, min) = find_min(tab);
+    // The first field is not used therefore we can replace it with "_"
+    min.print();
+}