1 class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             Contract.ContractFailed += (sender, e) =>
 6             {
 7                 Console.WriteLine("协定出错");
 8                 Console.WriteLine(e.Message);
 9                 e.SetHandled();
10             };
11 
12             int result = 0;
13             try
14             {
15                 result = sub(4, 5);
16             }
17             catch
18             {
19                 Console.WriteLine("Catch A Exception");
20             }
21             finally
22             {
23                 Console.WriteLine(result);
24             }
25 
26             Console.ReadLine();
27         }
28         public static int sub(int a, int b)
29         {
30             Contract.Requires(a > b, "fUCK YOU");
31 
32             return a - b;
33         }
34     }