C#方法的练习

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Demo1
{
    class Program
    {
        /// <summary>
        /// 求一个字符串数组中最长的元素
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        public static string GetLongest(string[] s)
        {
            string max = s[0];
            for (int i = 0; i < s.Length; i++)
            {
                if (s[i].Length > max.Length)
                {
                    max = s[i];
                }
            }
            return max;
        }
        static void Main(string[] args)
        {
            //用方法来实现:有一个字符串数组:
            //{"马龙"，"迈克尔乔丹","雷吉米勒","科比"}，请输出最长的那个
            string[] names = { "马龙", "迈克尔乔丹", "雷吉米勒", "科比" };
            Console.WriteLine(GetLongest(names));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Demo1
{
    class sumnumber
    {
        /// <summary>
        /// 计算出整数数组的平均值并保留2位小数
        /// </summary>
        /// <param name="nums"></param>
        /// <returns></returns>
        public double GetAvg(int[] nums)
        {
            double sum = 0;
            for (int i = 0; i < nums.Length;i++ )
            {
                sum += nums[i];
            }
            return sum / nums.Length;
        }
    }
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Demo1
{
    class Program
    {    
        static void Main(string[] args)
        {
            int[] numbers = { 1, 2, 7 };
            sumnumber sber = new sumnumber();
            double avg = sber.GetAvg(numbers);
            //保留2位小数  将avg转换成string类型
            //然后用Convet.ToDouble转换
            string str=avg.ToString("0.00");
            avg = Convert.ToDouble(str);
            Console.WriteLine(avg);
            Console.ReadKey();
        }
    }
}