C# 学习

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

namespace ConsoleApp2
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //变量
            int num = 1;
            char c = 'a';
            float f = 1.1f;
            double a = 22.3;
            string str = "我是tom";
            bool b = false;
            Console.WriteLine(num);
            Console.WriteLine(c);
            Console.WriteLine(f);
            Console.WriteLine(a);
            Console.WriteLine(a+c);
            Console.WriteLine(a+num);
            Console.WriteLine(str);
            Console.WriteLine(b);
       
            //常量
            const int num2 = 30;
            Console.WriteLine(num2);

            //> >= = < <=
            
            Console.WriteLine(1>2);
            Console.WriteLine(1 < 2);
            Console.WriteLine(a>c);

            //==
            Console.WriteLine(1==2);
            Console.WriteLine(1 != 2);

            int n1 = 10;
            int n2 = n1++;
            int n3 = ++n1;
            Console.WriteLine(n1);
            Console.WriteLine(n2);
            Console.WriteLine(n3);

            int n4 = 10;
            n4 += 5;
            Console.WriteLine(n4);
            int n5 = 15;
            Console.WriteLine(n5%5);
            int n6;
            n6 = n4 + n5;
            Console.WriteLine(n6);
            string s1 = "123";
            string s2 = "ja1";
            Console.WriteLine(s1+s2);
            Console.WriteLine("{0},{1},{2}",n1,s1,n5);
            //类型转换
            int n7 = 10;
            //隐式转换
            float n8 = n7;
            Console.WriteLine(n8);
            float n9 = 1.1f;
            //显示转换
            int n10 =(int)n9;
            Console.WriteLine(n10);
            //Convert转换
            string s3 = "35";
            int n12 = Convert.ToInt32(s3);
            Console.WriteLine(n12);
            double n13 = Convert.ToDouble(s3);
            Console.WriteLine(n13);

            int n14 = 5;

            if (n14==0)
            {
                Console.WriteLine("是0啊");
            }else if (n14==8)
            {
                Console.WriteLine("是8啊");
            }
            else
            {
                Console.WriteLine("是{0}啊",n14);
            }

            Console.WriteLine("\"a\"d\ts是\n{0}啊", n14);

            int n15 = 1;
            MyDate m = MyDate.Fri;
            Console.WriteLine("是{0},{1}啊", m,(int)m);
            switch ((int)m)
            {
                case 1:
                    Console.WriteLine(1);
                    break;
                case 2:
                    Console.WriteLine(2);
                    break;
                default:
                    Console.WriteLine(m);
                    break;
            }
            //for循环
            int n16 = 0;
            for (int i = 1; i < 101; i++)
            {
                n16 += i;
            }
            Console.WriteLine(n16);
            //while
            int n17 = 5;
            while (n17>0)
            {
                Console.WriteLine(n17);
                n17--;
                
            }
            Console.WriteLine("结束while循环");
            // do while
            do
            {
                Console.WriteLine(n17);
                n17--;
            } while (n17 > 0);
            Console.WriteLine("结束dowhile循环");
            //数组
            //创建数组
            int[] arr1=new int[3];
            Console.WriteLine(arr1);
            int[] arr2 = new int[3] {1,2,3};
            Console.WriteLine(arr2[0]);
            int[] arr3 = new int[] { 1, 2, 3 };
            Console.WriteLine(arr3[0]);
            int[] arr4 = { 4,5,1, 2, 3 };
            Console.WriteLine(arr4[2]);
            int b22 = arr4.Length;
            Console.WriteLine(b22);
            Console.WriteLine("-------------------------------------");
            //遍历数组 
            //foreach
            foreach (var item in arr4)
            {   
                Console.WriteLine((item+1));
            }
            //冒泡排序
            int temp;
            for (int j = 0; j < arr4.Length-1; j++)
            {
                for (int i = 0;i < arr4.Length - 1-j;i++)
                {
                    if (arr4[i] > arr4[i+1])
                    {
                        temp = arr4[i +1];
                        arr4[i + 1] = arr4[i];
                        arr4[i] = temp;
                    }
                }
            }
            foreach (var item in arr4)
            {
                Console.WriteLine((item));
            }
            Console.ReadKey();
        }
      


        
        enum MyDate
        {
            //枚举类型
            //enum
            //枚举类型 是一种独特的值类型,它用于声明相同性质的常量
            //作用:可以增加程序的可读性和可维护性,同时还能避免类型错误

            Mon = 0,
            Tue = 1,
            Wed = 2,
            Thu = 3,
            Fri = 4,
            Sat = 5,
            Sun = 6
        }
    }
}