Microsoft PowerPoint - 3ÀÏÂ°_º¯¼ö¿Í »ó¼ö.ppt

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1 변수와상수 1

2 변수란무엇인가? 변수 : 정보 (data) 를저장하는컴퓨터내의특정위치 ( 임시저장공간 ) 메모리, register 메모리주소 101 번지 102 번지 변수의크기에따라 주로 byte 단위 메모리 2

3 기본적인변수형및변수의크기 변수의크기 해당컴퓨터에서는항상일정 컴퓨터마다다를수있음 short <= int <= long signed vs. unsigned signed 가 default 3

4 변수형 형태 bool unsigned short int short int unsigned long int long int int(16비트 ) int(32비트 ) unsigned int(16비트 ) unsigned int(32비트 ) char float double 크기 1바이트 2바이트 2바이트 4바이트 4바이트 2바이트 4바이트 2바이트 4바이트 1바이트 4바이트 8바이트 값참 / 거짓 0 ~ 65,535-32,768 ~ 32,767 0 ~ 4,294,967,295-2,147,483,648 ~ 2,147,483,647-32,768 ~ 32,767-2,147,483,648 ~ 2,147,483,647 0 ~ 65,535 0 ~ 4,294,967, 개의문자값 (ASCII) 1.2e-38 ~ 3.4e38 2.2e-308 ~ 1.8e308 4

5 #include <iostream> int main() { using std::cout; cout << "The size of an int is:\t\t" << sizeof(int) << " bytes.\n"; cout << "The size of a short int is:\t" << sizeof(short) << " bytes.\n"; cout << "The size of a long int is:\t" << sizeof(long) << " bytes.\n"; cout << "The size of a char is:\t\t" << sizeof(char) << " bytes.\n"; cout << "The size of a float is:\t\t" << sizeof(float) << " bytes.\n"; cout << "The size of a double is:\t" << sizeof(double) << " bytes.\n"; cout << "The size of a bool is:\t" << sizeof(bool) << " bytes.\n"; } return 0; 5

6 변수정의하기 예 int myage; int myage, myweight, myheight; 의미있는단어사용 int main() { unsigned short x, y, z; z = x*y; return 0; } 대소문자구별 int age, Age; // No syntax error 작성법 int my_age; int myage; int imyage; 예약어사용금지 int, if, while, for, main int main() { unsigned short Width; unsigned short Height; unsigned short Area; Area = Width * Length; return 0; } 6

7 변수에값할당 vs. 초기화 할당 ( 값대입 ) unsigned short Width; Width = 5; 정의할때초기화 unsigned short Width =5; long width = 5, length = 7; int myage=39, yourage, hisage=40; 7

8 // list 3.3 #include <iostream> int main() { using std::cout; using std::endl; unsigned short int Width = 5, Length; Length = 10; // create an unsigned short and initialize with result // of multiplying Width by Length unsigned short int Area = Width * Length; } cout << "Width:" << Width << "\n"; cout << "Length: " << Length << endl; cout << "Area: " << Area << endl; return 0; 8

9 typedef 변수별칭 : typedef typedef unsigned short int USHORT 9

10 // list 3.3 #include <iostream> typedef unsigned short int USHORT; //typedef defined int main() { using std::cout; using std::endl; } USHORT Width = 5; USHORT Length; Length = 10; USHORT Area = Width * Length; cout << "Width:" << Width << "\n"; cout << "Length: " << Length << endl; cout << "Area: " << Area <<endl; return 0; 10

11 변수사용 short vs. long unsigned vs. signed float vs. int unsigned 정수형올림초기화 signed 정수형올림초기화 11

12 변수사용 (cont.) 이진표현 unsigned signed N is represented by 2 s complement, N* N*=2 n -N 12

13 //list 3.4 #include <iostream> int main() { using std::cout; using std::endl; } unsigned short int smallnumber; smallnumber = 65535; cout << "small number:" << smallnumber << endl; smallnumber++; cout << "small number:" << smallnumber << endl; smallnumber++; cout << "small number:" << smallnumber << endl; return 0; small number : small number : 0 small number : 1 13

14 //list 3.5 #include <iostream> int main() { short int smallnumber; smallnumber = 32767; std::cout << "small number:" << smallnumber << std::endl; smallnumber++; std::cout << "small number:" << smallnumber << std::endl; smallnumber++; std::cout << "small number:" << smallnumber << std::endl; return 0; } small number : small number : small number :

15 문자 (character) 1 바이트 256개의문자가능 0~255까지의숫자또는 ASCII 문자형으로해석 97 a 53 5 문자초기화 char mychar= a ; 특수출력문자 \a 벨소리 \ 작은따옴표 \b backspace \ 큰따옴표 \f form feed \` 홑따옴표 \n 개행문자 \? 의문부호 \r Carriage return \\ 역사선 \t 탭 \000 8 진법표시 \v 수직탭 \xhhh 16 진법표시 15

16 //list 3.6 #include <iostream> int main() { for (int i = 32; i<128; i++) std::cout << (char) i; return 0; } 16

17 상수 (Constant) 문자상수 : 입력값 int myage = 39 ; 기호상수 : 이름에의해표시 ( 유지보수의편이 ) student = classes * 15; students = classes * studentperclass; #define 을가지고상수를정의하는법 형 (type) 을가질수없음 #define studentperclass 15 const 로상수 형을가질수있음 const unsigned short int studentperclass = 15; 17

18 나열형상수 특정값으로제한된변수명 Ex) COLOR -> RED, BLUE, GREEN enum COLOR {RED, BLUE, GREEN, WHITE, BLACK} 정수값과일치 enum COLOR {RED=100, BLUE, GREEN=500, WHITE, BLACK=700}

19 // list 3.7 #include <iostream> int main() { enum Days { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }; Days today; today = Monday; if (today == Sunday today == Saturday) std::cout << "\ngotta' love the weekends!\n"; else std::cout << "\nback to work.\n"; } return 0; 19

20 // list 3.8 #include <iostream> int main() { const int Sunday = 0; const int Monday = 1; const int Tuesday = 2; const int Wednesday = 3; const int Thursday = 4; const int Friday = 5; const int Saturday = 6; int today; today = Monday; if (today == Sunday today == Saturday) std::cout << "\ngotta' love the weekends!\n"; else std::cout << "\nback to work.\n"; } return 0; 20

K&R2 Reference Manual 번역본

K&R2 Reference Manual 번역본 typewriter structunion struct union if-else if if else if if else if if if if else else ; auto register static extern typedef void char short int long float double signed unsigned const volatile { } struct