Introduction to Programming Language

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1 Introduction to Programming Language
Python Introduction to Programming Language

2 Introduction to Programming Language
Python Programs a program is a sequence of definitions and commands 프로그램은 정의와 명령의 연속임 definitions evaluated 정의에 따라 평가됨 commands executed by Python interpreter in a shell 명령은 해석기가 실행함 commands (statements) instruct interpreter to do something 명령에 따라 해석기가 동작함 can be typed directly in a shell or stored in a file that is read into the shell and evaluated 쉘에서 직접 쓸 수도 있고, 파일에 저장해서 읽히도록 할 수도 있음 Introduction to Programming Language

3 Introduction to Programming Language
Objects Python program manipulates data objects 객체를 조작함 Objects have a type that defines the kinds of things program can do to them 객체에 프로그램에 정의된 여러 동작을 적용할 수 있음 objects are 객체는 수와 수가 아닌 것을 포함함 scalar (cannot be subdivided) non-scalar Introduction to Programming Language

4 Introduction to Programming Language
Scalar objects int – represent integers, ex. 1, 2, 3, 4, etc. 정수 float – represent real numbers, ex. 3.14, 실수 bool – represent Boolean values True and False 논리 값 can use type() to see the type of an object type이라는 명령어로 형을 알 수 있음 >>> type(5) int >>> type(3.14) float Introduction to Programming Language

5 Type conversion (cast)
can convert object of one type to another 자신의 형이 아닌 다른 형으로 변환 가능함 example: 예 float(3) converts integer 3 to float(3.0) 정수를 실수로 바꿈 int(3.9) truncates float 3.9 to integer 3 실수를 정수로 바꿈 Introduction to Programming Language

6 Introduction to Programming Language
Printing to console to show output from code to a user, use print command print 명령으로 출력할 수 있음 In [30]: 3+8 Out [30]: 11 In [31]: print(3+8) 11 “out” tells you it’s an interaction within the shell only No “out” means it is actually shown to a user when you run a file Introduction to Programming Language

7 Introduction to Programming Language
Expressions combines objects and operators to form expressions 연산자와 객체를 조합하여 표현식을 만들 수 있음 an expression has a value, which has a type 표현식은 형을 갖는 값 syntax for a simple expression 간단한 표현식의 문법 <object> <operator> <object> Introduction to Programming Language

8 Operators for int and float types
i + j  sum, int->int, float->float i - j  difference , int->int, float->float i * j  product , int->int, float->float i / j  division, result is always float i % j  the modular operator, it gives remainder when I is divided by j 나머지 연산자, i ** j  I to the power of j 승을 계산 Introduction to Programming Language

9 Binding variables and values
equal sign is an assignment of a value to a variable name 등호를 써서 변수 이름에 값을 할당함 value stored in computer memory 값은 컴퓨터 메모리에 저장됨 an assignment binds name to value 할당으로 이름과 값을 연결 retrieve value associated with name or variable by invoking the name, by typing pi 이름을 부르면 연결된 값을 읽어옴 pi = pi_approx = 22/7 Introduction to Programming Language

10 Abstracting expressions
Why give names to values of expressions? 변수를 사용하여 수식을 표현하는 이유 to reuse names instead of values 값이 아니라 이름으로 재사용 가능하도록 easier to change the code later 코드의 변경이 쉬움 pi = radious = 2.2 area = pi*(radious**2) Introduction to Programming Language