C#数据结构之串

　　串（string）是n（n>=0）个字符组成的有限序列。

　　由于串中的字符都是连续存储的，在C#中有恒定不变的特性。一经创建就保持不变。

　　为了区别C#中的string，因此以stringDS类模拟string的数据结构，代码如下：

class stringDS
    {
        private char[] _data;
        //字符数组
        
        //索引器
        public char this[int index] {
            get {
                return _data[index];
            }
            set {
                _data[index] = value;
            }
        }
        
        //构造函数
        public stringDS(char[] arr)
        {
            _data = new char[arr.Length];
            for (int i = 0; i < arr.Length; i++) {
                _data[i] = arr[i];
            }
        }
        
        //构造函数
        public stringDS(int len)
        {
            char[] arr = new char[len];
            _data = arr;
        }
        
        //求串长
        public int GetLength()
        {
            return _data.Length;
        }
        
        //串比较
        public int Compare(stringDS s)
        {
            int len = (this.GetLength() <= s.GetLength()) ? this.GetLength() : s.GetLength();
//            len=len-1;
            int i = 0;
            for(i=0;i<len;i++)
            {
                if(this[i]!=s[i])
                {
                    break;
                }
            }
            if (i < len) {
                if (this[i] < s[i]) {
                    return -1;
                } else if (this[i] > s[i]) {
                    return 1;
                }
            } else if (this.GetLength() == s.GetLength()) {
                return 0;
            } else if (this.GetLength() < s.GetLength()) {
                return -1;
            }
            return 1;
        }
        
        //求子串
        public stringDS SubString(int index, int len)
        {
            if (index < 0 || index > (this.GetLength() - 1)
                || len < 0 || len > (this.GetLength() - index)) {
                Console.WriteLine("position or len is error!");
                return null;
            }
            stringDS s = new stringDS(len);
            for (int i = 0; i < len;++i) {
                s[i] = this[i + index];
            }
            return s;
        }
        
        //串连接
        public stringDS Concat(stringDS s)
        {
            stringDS s1 = new stringDS(this.GetLength() + s.GetLength());
            for (int i = 0; i < this.GetLength(); i++) {
                s1._data[i] = this[i];
            }
            for (int i = 0; i < s.GetLength(); i++) {
                s1._data[this.GetLength() + i] = s[i];
            }
            return s1;
        }
        
        //串插入
        public stringDS Insert(int index, stringDS s)
        {
            int len = s.GetLength();
            int len2 = len + this.GetLength();
            stringDS s1 = new stringDS(len2);
            if (index < 0 || index > this.GetLength() - 1) {
                Console.WriteLine("Position is error!");
                return null;
            }
            for (int i = 0; i < index; i++) {
                s1[i] = this[i];
            }
            for (int i = index; i < index + len; i++) {
                s1[i] = s[i - index];
            }
            for (int i = index + len; i < len2; i++) {
                s1[i] = this[i - len];
            }
            return s1;
        }
        
        //串删除
        public stringDS Delete(int index, int len)
        {
            if (index < 0 || index > (this.GetLength() - 1)
                || len < 0 || len > (this.GetLength() - index)) {
                Console.WriteLine("position or len is error!");
                return null;
            }
            stringDS s = new stringDS(this.GetLength() - len);
            for (int i = 0; i < index; i++) {
                s[i] = this[i];
            }
            for (int i = index + len; i < this.GetLength(); i++) {
                s[i] = this[i];
            }
            return s;
        }
        
        //串定位
        public int Index(stringDS s)
        {
            if (this.GetLength() < s.GetLength()) {
                Console.WriteLine("There is not string s!");
                return -1;
            }
            int i = 0;
            int len = this.GetLength() - s.GetLength();
            while (i< len) {
                stringDS temp=this.SubString(i,s.GetLength());
                if (temp.Compare(s) == 0) {
                    break;
                }
                i++;
            }
            if (i <= len) {
                return i;
            }
            return -1;
        }
            
    }