Add game loops and betting

30_Cube/csharp/IOExtensions.cs

@@ -0,0 +1,20 @@
+namespace Cube;
+
+internal static class IOExtensions
+{
+    internal static float? ReadWager(this IReadWrite io, float balance)
+    {
+        io.Write(Streams.Wager);
+        if (io.ReadNumber("") == 0) { return null; }
+
+        var prompt = Prompts.HowMuch;
+
+        while(true)
+        {
+            var wager = io.ReadNumber(prompt);
+            if (wager <= balance) { return wager; }
+
+            prompt = Prompts.BetAgain;
+        }
+    }
+}