Week one: Introduction to Python

1. What does a computer do?

   Calculations and Store

2. Types of Knowledge

   Declarative knowledge is statements of fact.

   Imperative knowledge is a recipe or “how-to” knowledge

3. What is a recipe?

   1. sequence of simple steps

   2. flow of control process that specifies when each step is executed

   3. a means of determining when to stop

      STEPS 1+2+3 = an algorithm

4. Aspects of LANGUAGES

   numbers,strings,simple operations.

   • syntax

     • English:”Cat dog boy” > not syntactically valid

       ​ “Cat hugs boy” > syntactically valid

     • Programming language: “hi” * 5 > not syntactically valid

       3.2 * 5 > syntactically valid

5. Where things go wrong

   • syntactic errors
   • static semantic errors
   • no semantic errors but different meaning than what programmer intended

6. Objects

   • Programs manipulate data objects

   • Objects have a ==type== that defines the kinds of things programs can do to them.

   • objects are

     • scalar (cannot be subdivided) 标量（有数值，无方向）
     • non-scalar(have internal structure that can be accessed)

   • Scalar objects

     • int — integers整数型:5
     • float — real numbers浮点型: 3.27
     • bool— BOOLEAN VALUES布尔型: True and False
     • NoneType — special and has one value: None

7. ‘for’ loop

   >>> for n in range(5):
   	print(n)
      
      	
   0
   1
   2
   3
   4