Finished task2 completly.

hw5/task2/src/lib.rs

@@ -0,0 +1,55 @@
+use std::fmt;
+#[derive(Debug)]
+pub struct Roman(String);
+
+impl fmt::Display for Roman {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl PartialEq<Roman> for &'static str {
+    fn eq(&self, roman: &Roman) -> bool {
+        self.to_string() == roman.0
+    }
+}
+
+impl From<i32> for Roman {
+    fn from(arabic_number: i32) -> Self {
+        let stages = vec![1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
+        let mut an = arabic_number;
+        let mut value = String::new();
+        for s in stages {
+            while an >= s {
+                value.push_str(&Roman::to_roman(s));
+                an -= s;
+            }
+        }
+        Roman::new(value)
+    }
+}
+
+impl Roman {
+    fn to_roman(number: i32) -> String {
+        match number {
+            1 => "I",
+            4 => "IV",
+            5 => "V",
+            9 => "IX",
+            10 => "X",
+            40 => "XL",
+            50 => "L",
+            90 => "XC",
+            100 => "C",
+            400 => "CD",
+            500 => "D",
+            900 => "CM",
+            1000 => "M",
+            _ => "",
+        }.to_string()
+    }
+
+    fn new(string: String) -> Self {
+        Roman(string)
+    }
+}