栈的顺序存储结构_C#实现3［数组实现］

//栈空条件:  this._size == -1
//栈满条件:  this.Count == this._array.Length

//自己改了一下, this._size 直接指向栈顶元素

using System;
namespace Stack
{
    class Stack2
    {
        //成员
        private object[] _array;                   //存放元素的数组
        private const int _defaultCapacity = 10;   //默认空间
        private int _size;                            //指向栈顶元素

        //属性
        public virtual int Count        //元素个数
        {
            get
            {
                return (this._size + 1);
            }
        }

        //构造器
        public Stack2()
        {
            this._array = new object[_defaultCapacity];
            this._size = -1;

        }
        public Stack2(int initialCapacity)
        {
            if (initialCapacity < 0)
            {
                throw new ArgumentOutOfRangeException("栈空间不能小于零");
            }
            if (initialCapacity < _defaultCapacity)
            {
                initialCapacity = _defaultCapacity;
            }
            this._array = new object[initialCapacity];    //分配栈空间
            this._size = -1;
        }

        //方法
        public virtual object Pop()                       //出栈
        {
            if (this._size == -1)
            {
                throw new ArgumentOutOfRangeException("栈下溢");
            }
            object obj2 = this._array[this._size];          //取栈顶元素
            this._array[this._size--] = null;               //删除栈顶元素
            return obj2;

        }
        public virtual void Push(object obj)              //进栈
        {
            if (this.Count  == this._array.Length)
            {
                object[] destinationArray = new object[2 * this._array.Length];    //空间满则扩容为原来的2倍
                Array.Copy(this._array, 0, destinationArray, 0, this.Count );
                this._array = destinationArray;
            }

            this._array[++this._size] = obj;              //进栈

        }

    }
}