be

Letter.cs

@@ -0,0 +1,28 @@
+namespace Prac7Meow
+{
+    internal class Letter
+    {
+        public int Number { get; }
+        public string Sender { get; }
+        public string Recipient { get; }
+        public double Weight { get; }
+        public int TermDays { get; }
+
+        public Letter(int number, string sender, string recipient, double weight, int termDays)
+        {
+            if (number <= 0)                          throw new ArgumentOutOfRangeException( nameof(number),             "Number must be > 0"   );
+            if (string.IsNullOrWhiteSpace(sender))    throw new ArgumentException(           "Sender can't be empty",    nameof(sender)         );
+            if (string.IsNullOrWhiteSpace(recipient)) throw new ArgumentException(           "Recipient can't be empty", nameof(recipient)      );
+            if (weight <= 0)                          throw new ArgumentOutOfRangeException( nameof(weight),             "Weight must be > 0"   );
+            if (termDays <= 0)                        throw new ArgumentOutOfRangeException( nameof(termDays),           "TermDays must be > 0" );
+
+            Number    = number;
+            Sender    = sender;
+            Recipient = recipient;
+            Weight    = weight;
+            TermDays  = termDays;
+        }
+
+        public override string ToString() => $"Письмо #{Number}: {Sender} -> {Recipient}, {Weight:F1} г, срок {TermDays} дн.";
+    }
+}