用语言描述下面的程序，并举例说明程序运行的结果： class SampleParameter { public void Swap1(int x, int y) { int z = x; x = y; y = z; } public void Swap2(ref int x, ref int y) { int z = x; x = y; y = z; } public void Add(int x, int y, out int sum) { sum = x + y; } } class Program { static void Main(string[] args) { int a, b, c; Console.Write("请输入第一个数:"); a = int.Parse(Console.ReadLine()); Console.Write("请输入第二个数:"); b = int.Parse(Console.ReadLine()); SampleParameter smpParameter = new SampleParameter(); smpParameter.Swap1(a, b); Console.WriteLine("交换结果是{0},{1}", a, b); smpParameter.Swap2(ref a, ref b); Console.WriteLine("交换结果是{0},{1}", a, b); smpParameter.Add(a, b, out c); Console.WriteLine("输出结果是{0}", c); Console.ReadLine(); } }