栈与堆

栈是编译期间就分配好的内存空间，因此代码中必须就栈的大小有明确的定义；局部值类型变量、值类型参数等都在栈内存中
堆是程序运行期间动态分配的内存空间，可以根据程序的运行情况确定要分配的堆内存的大小
                        #region a->b->c->d 输出 d,c,b,a
                        string[] names = new string[] { "a", "b", "c", "d" };
                        Stack stack = new Stack();
                        foreach (string item in names)
                        {
                                stack.Push(item);
                        }
                        while (stack.Count > 0)
                        {
                                Console.WriteLine(stack.Pop());
                        }
                        #endregion