這裡我預計要寫做出選擇和決定時會用的語法

1. IF語句-->if~else

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
            string userName = "";
            int userAge = 0;
            int currentYear = 0;

            Console.WriteLine("請輸入您的名字:");
            userName = Console.ReadLine();

            Console.WriteLine("輸入您的年齡:");
            userAge = Convert.ToInt32(Console.ReadLine());

            if(userAge <0 || userAge > 100)
            {
                Console.WriteLine("不可能年齡");
                Console.WriteLine("必須要在1-100之間");
            }
            else if(userAge < 18)
            {
                Console.WriteLine("抱歉您的年齡太小");
            }

            else if (userAge < 21)
            {
                Console.WriteLine("需要家長同意");
            }
            else 
            {
                Console.WriteLine("恭喜您可以登入");
            }
        }
    }
}

2. Switch

break 就是跳出

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
            Console.WriteLine("輸入您的等級:");
            string userGrade = Console.ReadLine();

            switch (userGrade)
            {
                case "A":
                    Console.WriteLine("優秀");
                    break;

                case "B":
                    Console.WriteLine("B級");
                    break;

                case "C":
                    Console.WriteLine("C級");
                    break;
                    default:
                    Console.WriteLine("Fail");
                    break;


            }
        }
    }
}

3. For Loop循環-不斷的重複直到滿足條件

這裡是每一行i+1

顯示0-4

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
           for (int i = 0; i < 5; i++)
            {
                Console.WriteLine(i);
            }


            }
        }
    }

顯示[]裡面的數字

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
            int[] myNumber = { 10, 20, 30,40,50 };

           for (int i = 0; i < myNumber.Length; i++)
            {
                Console.WriteLine(myNumber[i]);
            }


            }
        }
    }

4. Foreach Loop循環-依序把字印出來

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
            char[] message = { 'H', 'e', 'l', 'l', 'o'};

            foreach (char i in message) { Console.WriteLine(i); 
            }
           


            }
        }
    }

5. Whlie 循環-當條件有效時循環

用--來-1

using System;


namespace HelloWorld2
{
     class Program
    {
        public static void Main(string[] args)

        {
            int counter = 5;

            while (counter > 0) { Console.WriteLine("Counter ={0}",counter);
            counter--;
            }
       
           


            }
        }
    }

6. Do While-至少執行一次

7. Break
8. Continue

其實這些都是我原本迷路的地方可能要分兩篇

DEAR ALL 我們明天見