20190324-C#學習日誌

//自動換行
Console.WriteLine("Hello ");

Console.WriteLine("How are you?");

//不會自動換行

Console.Write("Hello ");

Console.Write("How are you?");

//如果開頭加入
using static System.Console;

//將不必再輸入Console

WriteLine("Hello ");

WriteLine("How are you?");

//將變數列印到螢幕中

int userAge = 30;

Console.WriteLine(userAge);

//連接字串並列印到螢幕中

Console.WriteLine("Hello, " + "how are you?" + " I love C#.");

int results = 79;
Console.WriteLine("You scored " + results + " marks for your test.");

Console.WriteLine("You scored {0} marks for your test. {1}", results, "Congratulations!");

Console.WriteLine("You scored {0:F3} marks for yout test.", 123.45678);

Console.WriteLine("You have {0:C} dollars.", 2111);

/*--------------------------------------------------------------------------------------------------*/

//跳脫字元

//Tab
Console.WriteLine("Hello\tWorld");

//換行
Console.WriteLine("Hello\nWorld");

//顯示\
Console.WriteLine("\\");

//顯示"
Console.WriteLine("\"Hello!\"");

/*--------------------------------------------------------------------------------------------------*/

//接受用戶輸入字串

String userInput = Console.ReadLine();

Console.WriteLine(userInput);

/*--------------------------------------------------------------------------------------------------*/

//將字串轉換為數值

String userInput = Console.ReadLine();

int newUserInput = Convert.ToInt32(userInput);

newUserInput++;

Console.WriteLine(newUserInput);

/*--------------------------------------------------------------------------------------------------*/

//之前的總結

using System;

namespace HelloWorld
{
    class MainClass
         public static void Main(string [] args)
         {
              string userName = "";
              int userAge = 0;
              int currentYear = 0;
 
              Console.WriteLine("Please enter your name: ");
              userName = Console.ReadLine();
 
              Console.WriteLine("Please enter your age: ");
              userAge = Convert.ToInt32(Console.ReadLine());
 
              Console.WriteLine("Please enter current year: ");
              currentYear = Convert.ToInt32(Console.ReadLine());

              Console.WriteLine("Hello World! My name is {0} and I am {1} " +
              "I was born in {2}.",
              userName, userAge,  currentYear - userAge);
         }
    }
}

/*--------------------------------------------------------------------------------------------------*/

// If and else

using System;

namespace HelloWorld
{
     class MainClass
     {
          public static void Main(string [] args)
          {
                int userAge = 0;
 
                Console.WriteLine("Please enter your age: ");
                userAge = Convert.ToInt32(Console.ReadLine());
 
                if( userAge < 0 || userAge > 100)
                {
                     Console.WriteLine("Invalid Age.");
                     Console.WriteLine("Age must be between 0 and 100.");
                }
                else if(userAge < 18)
                {
                     Console.WriteLine("Sorry, you are underage.");
                }
                else if(userAge < 21)
                {
                     Console.WriteLine("You need parental consent.");
                }
                else
                {
                     Console.WriteLine("Congratulations! You may sign up!");
                }
          }
     } }

/*--------------------------------------------------------------------------------------------------*/

// Switch

using System;

namespace HelloWorld
{
     class MainClass
     {
          public static void Main()
          {
               Console.WriteLine("Enter your grade:");
               string userGrade = Console.ReadLine();

               switch(userGrade)
               {
                    case "A":
                         Console.WriteLine("Distinction");
                         break;
                    case "B":
                         Console.WriteLine("B Grade");
                         break;
                    case "C":
                         Console.WriteLine("C Grade");
                         break;
                    default:
                         Console.WriteLine("Fail");
                         break;
               }
          }
     }
}