3일차

오늘도 어디 해 보실까

 

1. 실습_ArithmaticOperators

using System;

namespace _4장_ArithmaticOperators_119page
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 111 + 222;
            Console.WriteLine($"a: {a}");

            int b = a - 100;
            Console.WriteLine($"b: {b}");

            int c = b * 10;
            Console.WriteLine($"c: {c}");

            double d = c / 6.3;
            Console.WriteLine($"d: {d}");

            Console.WriteLine($"22/7={22 / 7}({22 % 7})");
        }
    }
}

 

2. 실습_IncDecOperator

using System;

namespace _4장_IncDecOperator_121page
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 10;
            Console.WriteLine(a++);
            Console.WriteLine(++a);

            Console.WriteLine(a--);
            Console.WriteLine(--a);
        }
    }
}

 

3. 실습_StringConcatenate

using System;

namespace _4장_StringConcatenate_123page
{
    class Program
    {
        static void Main(string[] args)
        {
            string result = "123" + "456";
            Console.WriteLine(result);

            result = "Hello" + " " + "World!";
            Console.WriteLine(result);
        }
    }
}

 

4. 실습_RelationalOperator

using System;

namespace _4장_RelationalOperator_124page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine($"3>4: {3>4}");
            Console.WriteLine($"3>=4: {3 >= 4}");
            Console.WriteLine($"3<4: {3 < 4}");
            Console.WriteLine($"3<=4: {3 <= 4}");
            Console.WriteLine($"3==4: {3 == 4}");
            Console.WriteLine($"3!=4: {3 != 4}");
        }
    }
}

 

5. 실습_LogicalOperator

using System;

namespace _4장_LogicalOperator_126page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Testing && ...");
            Console.WriteLine($"1>0 && 4<5:{1 > 0 && 4 < 5}");
            Console.WriteLine($"1>0 && 4>5:{1 > 0 && 4 > 5}");
            Console.WriteLine($"1==0 && 4>5:{1 == 0 && 4 > 5}");
            Console.WriteLine($"1==0 && 4<5:{1 == 0 && 4 < 5}");

            Console.WriteLine("\nTesting || ...");
            Console.WriteLine($"1>0 || 4<5:{1 > 0 || 4 < 5}");
            Console.WriteLine($"1>0 || 4>5:{1 > 0 || 4 > 5}");
            Console.WriteLine($"1==0 || 4>5:{1 == 0 || 4 > 5}");
            Console.WriteLine($"1==0 || 4<5:{1 == 0 || 4 < 5}");

            Console.WriteLine("\nTesting ! ...");
            Console.WriteLine($"!True: {!true}");
            Console.WriteLine($"!False: {!false}");
        }
    }
}

 

6. 실습_ConditionalOperator

using System;

namespace _4장_ConditionalOperator_128page
{
    class Program
    {
        static void Main(string[] args)
        {
            string result = (10 % 2) == 0 ? "짝수" : "홀수";
            Console.WriteLine(result);
        }
    }
}

 

7. 실습_NullConditionalOperator

using static System.Console;
using System.Collections;

namespace _4장_NullConditionalOperator_130page
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList a = null;
            a?.Add("야구"); // a가 null을 반환하므로 Add()는 호출되지 않음
            a?.Add("축구");
            WriteLine($"Count: {a?.Count}");
            WriteLine($"{a?[0]}");
            WriteLine($"{a?[1]}");

            a = new ArrayList(); // a는 더이상 null상태가 아님
            a?.Add("야구");
            a?.Add("축구");
            WriteLine($"Count: {a?.Count}");
            WriteLine($"{a?[0]}");
            WriteLine($"{a?[1]}");
        }
    }
}

 

8. 실습_ShiftOperator

using System;

namespace _4장_ShiftOperator_134page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Testing <<...");

            int a = 1;
            Console.WriteLine("a     :{0:D5} (0x{0:X8})", a);
            Console.WriteLine("a << 1:{0:D5} (0x{0:X8})", a << 1);
            Console.WriteLine("a << 2:{0:D5} (0x{0:X8})", a << 2);
            Console.WriteLine("a << 5:{0:D5} (0x{0:X8})", a << 5);

            Console.WriteLine("\nTesting >>...");

            int b = 255;
            Console.WriteLine("b     :{0:D5} (0x{0:X8})", b);
            Console.WriteLine("b >> 1:{0:D5} (0x{0:X8})", b >> 1);
            Console.WriteLine("b >> 2:{0:D5} (0x{0:X8})", b >> 2);
            Console.WriteLine("b >> 5:{0:D5} (0x{0:X8})", b >> 5);

            Console.WriteLine("\nTesting >> 2...");

            int c = -255;
            Console.WriteLine("c     :{0:D5} (0x{0:X8})", c);
            Console.WriteLine("c >> 1:{0:D5} (0x{0:X8})", c >> 1);
            Console.WriteLine("c >> 2:{0:D5} (0x{0:X8})", c >> 2);
            Console.WriteLine("c >> 5:{0:D5} (0x{0:X8})", c >> 5);
        }
    }
}

 

9. 실습_BitwiseOperator

using System;

namespace _4장_BitwiseOperator_138page
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 9;
            int b = 10;

            Console.WriteLine($"{a} & {b}: {a & b}");
            Console.WriteLine($"{a} | {b}: {a | b}");
            Console.WriteLine($"{a} ^ {b}: {a ^ b}");

            int c = 255;
            Console.WriteLine("~{0}(0x{0:X8}): {1}(0x{1:X8})", c, ~c);
        }
    }
}

 

10. 실습_AssignmentOperator

using System;

namespace _4장_AssignmentOperator_140page
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            a = 100;
            Console.WriteLine($"a=100: {a}");
            a += 90;
            Console.WriteLine($"a+=90: {a}");
            a -= 80;
            Console.WriteLine($"a-=80: {a}");
            a *= 70;
            Console.WriteLine($"a*=70: {a}");
            a /= 60;
            Console.WriteLine($"a/=60: {a}");
            a %= 50;
            Console.WriteLine($"a%=50: {a}");
            a &= 40;
            Console.WriteLine($"a&=40: {a}");
            a |= 30;
            Console.WriteLine($"a|=30: {a}");
            a ^= 20;
            Console.WriteLine($"a^=20: {a}");
            a <<= 10;
            Console.WriteLine($"a<<=10: {a}");
            a >>= 1;
            Console.WriteLine($"a>>=1: {a}");
        }
    }
}

 

11. 실습_NullCoalescing

using System;

namespace _4장_NullCoalescing_142page
{
    class Program
    {
        static void Main(string[] args)
        {
            int? num = null;
            Console.WriteLine($"{num ?? 0}");

            num = 99;
            Console.WriteLine($"{num ?? 0}");

            string str = null;
            Console.WriteLine($"{str ?? "Default"}");

            str = "Sepecific";
            Console.WriteLine($"{str ?? "Default"}");
        }
    }
}

 

12. 실습_IfElse

using System;

namespace _5장_IfElse_149page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("숫자를 입력하세요: ");

            string input = Console.ReadLine();
            int number = Int32.Parse(input);

            if (number < 0)
                Console.WriteLine("음수");
            else if(number >0)
                Console.WriteLine("양수");
            else
                Console.WriteLine("0");

            if ((number % 2) == 0)
                Console.WriteLine("짝수");
            else
                Console.WriteLine("홀수");
        }
    }
}

 

13. 실습_IfIf

using System;

namespace _5장_IfIf_151page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("숫자를 입력하세요: ");

            string input = Console.ReadLine();
            int number = Int32.Parse(input);

            if (number > 0)
            {
                if ((number % 2) == 0)
                    Console.WriteLine("0보다 큰 짝수");
                else
                    Console.WriteLine("0보다 큰 홀수");
            }
            else
                Console.WriteLine("0보다 작거나 같은 수");
        }
    }
}

 

14. 실습_Switch

using System;

namespace _5장_Switch_152page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("요일을 입력하세요.(일,월,화,수,목,금,토): ");
            string day = Console.ReadLine();

            switch (day) {
                case "일": Console.WriteLine("Sunday"); break;
                case "월": Console.WriteLine("Monday"); break;
                case "화": Console.WriteLine("Tuesday"); break;
                case "수": Console.WriteLine("Wednsday"); break;
                case "목": Console.WriteLine("Thursday"); break;
                case "금": Console.WriteLine("Friday"); break;
                case "토": Console.WriteLine("Saturday"); break;
                default: Console.WriteLine($"{day}는(은) 요일이 아닙니다."); break;
            }
        }
    }
}

 

15. 실습_Switch2

using System;

namespace _5장_Switch2_156page
{
    class Program
    {
        static void Main(string[] args)
        {
            object obj = null;

            string s = Console.ReadLine();
            if (int.TryParse(s, out int out_i))
                obj = out_i;
            else if (float.TryParse(s, out float out_f))
                obj = out_f;
            else
                obj = s;

            switch (obj) {
                case int i:
                    Console.WriteLine($"{i}는 int 형식입니다.");
                    break;
                case float f:
                    Console.WriteLine($"{f}는 float 형식입니다.");
                    break;
                default:
                    Console.WriteLine($"{obj}는 모르는 형식입니다.");
                    break;
            }
        }
    }
}

 

16. 실습_SwitchExp

using System;

namespace _5장_SwitchExp_161page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("점수를 입력하세요: ");
            int score = Convert.ToInt32(Console.ReadLine());

            Console.Write("재수강인가요? (y/n): ");
            string line = Console.ReadLine();
            bool repeated = line == "y" ? true : false;

            string grade = (int)(Math.Truncate(score / 10.0) * 10) switch
            {
                90 when repeated == true => "B+",
                90 => "A",
                80 => "B",
                70 => "C",
                60 => "D",
                _ => "F"
            };

            Console.WriteLine($"학점: {grade}");

        }
    }
}

짱이다...

 

17. 실습_While

using System;

namespace _5장_While_163page
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 10;

            while (i > 0)
                Console.WriteLine($"i: { i--}");
        }
    }
}

 

18. 실습_DoWhile

using System;

namespace _5장_DoWhile_166page
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 10;

            do
            {
                Console.WriteLine("a) i: {0}", i--);
            } while (i > 0);

            do
            {
                Console.WriteLine("b) i: {0}", i--);
            } while (i > 0);
        }
    }
}

 

19. 실습_For

using System;

namespace _5장_For_168page
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 0; i < 5; i++)
            { 
                Console.WriteLine(i);
            }
        }
    }
}

 

20. 실습_ForFor

using System;

namespace _5장_ForFor_169page
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 0; i < 5; i++)
            {
                for (int j = 0; j < 10; j++)
                    Console.Write("*");
                Console.WriteLine();
            }
        }
    }
}

 

21. 실습_ForEach

using System;

namespace _5장_ForEach_171page
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] arr = new int[] { 0, 1, 2, 3, 4 };
            
            foreach(int a in arr)
                Console.WriteLine(a);
        }
    }
}

 

22. 실습_InfiniteFor

using System;

namespace _5장_InfiniteFor_173page
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 0;
            for (; ; )
                Console.WriteLine(i++);
        }
    }
}

 

23. 실습_InfiniteWhile

using System;

namespace _5장_InfiniteWhile_173page
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 0;

            while(true)
                Console.WriteLine(i++);
        }
    }
}

 

24. 실습_Break

using System;

namespace _5장_Break_175page
{
    class Program
    {
        static void Main(string[] args)
        {
            while(true)
            {
                Console.Write("계속할까요? (예/아니오): ");
                string answer = Console.ReadLine();

                if (answer == "아니오") break;
            }
        }
    }
}

 

25. 실습_Continue

using System;

namespace _5장_Continue_176page
{
    class Program
    {
        static void Main(string[] args)
        {
            for(int i=0; i < 10;i++)
            {
                if (i % 2 == 0)
                    continue;
                Console.WriteLine($"{i}: 홀수");
            }
        }
    }
}

 

26. 실습_Goto

using System;

namespace _5장_Goto_179page
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("종료 조건(숫자)을 입력하세요: ");

            String input = Console.ReadLine();

            int input_number = Convert.ToInt32(input);
            int exit_number = 0;

            for(int i=0;i<2;i++)
            {
                for(int j=0;j<2;j++)
                {
                    for(int k=0;k<3;k++)
                    {
                        if (exit_number++ == input_number)
                            goto EXIT_FOR;

                        Console.WriteLine(exit_number);
                    }
                }
            }

            goto EXIT_PROGRAM;

        EXIT_FOR:
            Console.WriteLine("\nExit nested for...");

        EXIT_PROGRAM:
            Console.WriteLine("\nExit program...");

        }
    }
}

 

27. 연습문제1

using System;

namespace 연습문제1_182page
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 0; i < 5; i++)
            {
                for (int j = 0; j < i+1; j++)
                    Console.Write("*");
                Console.WriteLine();
            }
        }
    }
}

 

28. 연습문제2

using System;

namespace 연습문제2_182page
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 0; i < 5; i++)
            {
                for (int j = 5 - i; j > 0; j--)
                    Console.Write("*");
                Console.WriteLine();
            }
        }
    }
}

 

29. 연습문제3

using System;

namespace 연습문제3_182page
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 0, j=0;

            while(i<5)
            {
                Console.Write("*");
                if(++j > i)
                {
                    i++;
                    Console.WriteLine();
                    j = 0;
                }
            }

            Console.WriteLine();

            i = 0;
            j = 0;

            do {
                Console.Write("*");
                j++;
               
                if (5-j <= i)
                {
                    j = 0;
                    Console.WriteLine();
                    i++;
                }
            } while (i < 5);
        }
    }
}

 

30. 연습문제4

using System;

namespace 연습문제4_182page
{
    class Program
    {
        static void Main(string[] args)
        {
            int num = 0;
            do
            {
                Console.Write("반복 횟수를 입력하세요 : ");
                num = Convert.ToInt32(Console.ReadLine());
                if (num <= 0) Console.WriteLine("0보다 작거나 같은 수는 입력할 수 없습니다.\n");
            } while (num<=0);

            Console.WriteLine();
            for (int i = 0; i < num; i++)
            {
                for (int j = 0; j < i + 1; j++)
                    Console.Write("*");
                Console.WriteLine();
            }
        }
    }
}