데이터

• 기본데이터형식-복합데이터형식
• 값형식-참조형식
• 기본데이터형식

  • 	Type	Represents	Range	Default Value	example
    정수형	byte	8-bit unsigned integer	0 to 255	0	byte=255;
    	sbyte	8-bit signed integer type	-128 to 127	0	sbyte s=-128;
    	short	16-bit signed integer type	-32,768 to 32,767	0	short s=-32768;
    	ushort	16-bit unsigned integer type	0 to 65,535	0	ushort=65535;
    	int	32-bit signed integer type	-2,147,483,648 to 2,147,483,647	0	int i=-2147483,648;
    	uint	32-bit unsigned integer type	0 to 4,294,967,295	0	uint u=4294967295;
    	long	64-bit signed integer type	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	0L	long l=-9223372036854775808;
    	ulong	64-bit unsigned integer type	0 to 18,446,744,073,709,551,615	0	ulong u=10;
    실수형	float	32-bit single-precision floating point type	-3.4 x 1038 to + 3.4 x 1038	0.0F	1.0d/3:0.3333333 (7digits)
    	double	64-bit double-precision floating point type	(+/-)5.0 x 10-324 to (+/-)1.7 x 10308	0.0D	1.0/3:0.333~3(15~16digits)
    	decimal	128-bit precise decimal values with 28-29 significant digits	(-7.9 x 1028 to 7.9 x 1028) / 100 to 28	0.0M	1m/3:0.333~3 (28~29digits)
    문자형	char	16-bit Unicode character	U +0000 to U +ffff	'\0'	char c='a', d='국';
    불린형	bool	Boolean value	True or False	FALSE

               
• 형변환
  • 암시적 형변환 byte b=250; short s=b;  //250
  • 명시적형변환  ushort=40000; short s=(short)n; //-25536
• 상수형
  • const int a=0;
  • const int b=1;
  • const doible b=10;
• 열거형
  • enum DialogResult {Yes,No,Cancel=4, OK}
  • DialogResult dm=DialogResult.Yes;  
  • (int)DialogResult.Yes : 0        (int)DialogResult.No : 1 (int)DialogResult.Cencel : 4    (int)DialogResult.OK : 5
  • (string)DialogResult.Yes  => "Yes"
• nullable 형
  • int? length = customers?.Length; // null if customers is null
    Customer first = customers?[0];  // null if customers is null
    int? count = customers?[0]?.Orders?.Count();  // null if customers, the first customer, or Orders is null
    • int[] cs=null;
      int? len=cs.Length; //Error
      int? len=cs?.Length; //null 저장
    • int[] cs=new int[2];
      int? len=cs.Length; //2
      int? len=cs?.Length; //2 저장
• var 형
  • var a=3;       //컴파일러 자동 형 지정방식
    var b="Hello";

연산자

• 분류	연산자
  산술 연산자	+, -, *, /, %
  증가/감소 연산자	++, --
  관계 연산자	<, >, ==, !=, <=, >=
  조건 연산자	?:
  논리 연산자	&&, ||, !
  비트 연산자	<<, >>, &, |, ^, ~
  할당 연산자	=, +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=

제어문

• If - else 문
• switch(number)
  { 
      case 1 :  Console.WriteLIne(1); break;
      case 2 :  Console.WriteLIne(1); break;
     default  :  ;       
  }
• int sum = 0; int i = 0; 
  while (i <= 10) {
        sum += i++;
   } 
• int sum = 0; int i = 0; 
  do  {
           sum += i++;
   } while (i <= 10);
   Console.WriteLine(sum);
• int  sum = 0;
   for (int i = 0; i <= 10; i++)   {
          sum += i;
     }
    Console.WriteLine(sum); 
•  sum = i=0;
    Loop: sum += i;
           i++;
    if (i <= 10)
           goto Loop;
    Console.WriteLine(sum);
• int[] arr=new int[]{10,20)
  foreach(int n in arr)
      Console.writeLine(n); 
• break, continue 