day03 finishing

Finishing day 03

What is programming

Programming is write a bunch of files, control the direction of change of variables

Parameters, properties -> Variables

IPO

variable

What is variable

Variable describing the state of things in the world change

Variable is the concept of the interpreter provided only when running python

Compositional variables

+ + Variable name = variable value

Variable names fate specification

Variable names numbers, letters, underscores and can not start with a number, not name keyword

Two options for defining variables

Underline the word segmentation, llamas body separate words

constant

python constant and there is no convention in uppercase constants

Python memory management

Variable is defined in memory address space to open up a store

Reference count

Reference count number is variable reference value

Garbage collection

In the python would run [-5,256] first opened up for use, references to these will not be recovered 0

Other references to 0 by the system will reclaim the memory space

Three ways formatted output

f placeholders, format format, placeholders%

What is the data type

Data type is the classification of all the world state

Digital, character, dictionary, list, boolean

Digital Type

All things state numerical value

Defined way

A = 77

Instructions

​ + - * / // % **

String

Description of the state of things in the world

definition

name = 'ssssss'

Instructions

Addition multiplication * +

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Origin www.cnblogs.com/kaizi111/p/11520145.html