前端工程师养成手册——基础学习——第一周小结

Posted 2020-10-08

第五章关键点总结

数组与集合的对比

1、都是用来保存多个同类型的数据，数组具有定长性，而集合不具有定长性，因此保存数量固定的数据时可以用数组，数量会发生变化的可以用集合；

2、数组建立后，每一项为该数据类型的默认值；而集合建立后，当中没有元素，因为长度为0；

3、数组分析器 代码：

static void Main(string[] args)
        {
            int[] nums;
            int len;
            #region 创建数组
            while (true)
            {
                Console.Write("请输入数组的长度：");
                len = int.Parse(Console.ReadLine());
                nums = new int[len];
                if (len >= 0 && len <= 9999)
                {

                    break;
                }
                else
                {
                    Console.WriteLine("输入有误，回车继续输入");
                    Console.ReadLine();
                    Console.Clear();
                }
            }
            for (int i = 0; i < nums.Length; i++)
            {
                Console.Write("请输入数组的第" + (i + 1) + "项:");
                nums[i] = int.Parse(Console.ReadLine());
            }
            #endregion
            Console.Clear();
            #region 升序排列
            for (int i = 0; i < nums.Length - 1; i++)
            {
                for (int j = i + 1; j < nums.Length; j++)
                {
                    if (nums[i] > nums[j])
                    {
                        int temp = nums[i];
                        nums[i] = nums[j];
                        nums[j] = temp;
                    }
                }
            }
            #endregion
            #region 输出数组
            Console.WriteLine("你输入的数组排序如下:");
            for (int i = 0; i < nums.Length; i++)
            {
                Console.Write(nums[i] + " ");
            }
            Console.WriteLine();

            #endregion
            #region 寻找奇数
            Console.WriteLine("其中，以下数字是奇数：");
            for (int i = 0; i < nums.Length; i++)
            {
                if (nums[i] % 2 != 0)
                {
                    Console.Write(nums[i] + " ");
                }
            }
            Console.WriteLine();
            #endregion
            #region 寻找质数
            Console.WriteLine("其中以下数字是质数：");
            for (int i = 0; i < nums.Length; i++)
            {
                bool isFind = false;
                for (int j = 2; j < nums[i]; j++)
                {
                    if (nums[i] % j == 0)
                    {
                        isFind = true;
                        break;
                    }

                }
                if (!isFind)
                {
                    Console.Write(nums[i] + " ");
                }
            }

            #endregion
            Console.ReadLine();
        }