Study from the beginning of Python Hour1: Hello World

Studying Python Hour1: Hello World

• When I tried to do something with Python, I first searched for a sample script and somehow executed it.
• 7 hours I want to hit REST API with automatic execution, check the result, and even operate the VM

Learning materials

• Learn the basics in just one day! A super introduction to Python
• https://a.r10.to/hbHMiv

environment

• Windows
• Python Ver3 series

Basics

Installation

• It's not particularly difficult, so download it and follow the wizard
• If you search for "Python installation"
• http://www.python.org
• Check "Add environment variable" Check "Add Python 3.X to PATH"

Start Python

• Aside from autorun and double-click execution, execute interactively

• Start with command prompt / PowerShell

  C:\>python
  Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
  Type "help", "copyright", "credits" or "license" for more information.
  >>>
  >>>
  

Hello World

• Just hit the command

  C:\>python
  Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
  Type "help", "copyright", "credits" or "license" for more information.
  >>>
  >>> print("Hello Python!!")
  Hello Python!!
  >>>
  

variable

• Variable assignment

• Variable declaration / assignment / can be used many times / can be overwritten

  >>>###Calculate by substituting 10 for the variable hogeo
  >>> hogeo=10
  >>>
  >>> hogeo+5
  15
  >>>###Variables can be retrieved many times
  >>> hogeo *20
  200
  >>>###Variables can be overwritten
  >>> hogeo=5
  >>> hogeo+10
  15
  >>>

• Isn't there a type or declaration? I had a question

• Variables have no type. The assigned value itself has a type. is what they said

• Concept of variable rules and naming conventions

• The following variables are NG

• Reserved words (reserved words if or NG in Python)

• Variable name starting with a number (1a or NG)

• Naming convention (Imitating a person's naming convention should make it more readable!)

• Consists of English words and separates the words with "_"

• Example) Consumption tax: tax_rate

• Do not use uppercase alphabets (use constants below)

• Do not start with _

• Nodame cantabile abc or a

• Constant (variable that cannot be overwritten in other languages)

• Python allows you to override constants. This is because Python does not have a function called constants.

• It seems that it is common to say "variables with only uppercase letters and numbers are treated as constants". <<< This kind of thing is quite important, isn't it?

>>>###A crappy example of price calculation
>>> price=100
>>> price*1.1
110
>>>
>>>###A good example using constants
>>> price=100
>>> TAX_RATE=1.08
>>> price * TAX＿RATE
108.0
>>>

Variable type / type conversion

• String

• "'" "" "Enclose in single or double quotes

• In this book, I will enclose it in "'" single quotes after this, so I wonder if this is better

• Seems to use each other when dealing with "'" and "" "as strings

• String manipulation

>>> firstname='hogeo'
>>> lastname='matsumo'
>>> name=firstname+' '+lastname
>>> print(name)
hogeo matsumo
>>>

• Type conversion
• Price: When you want to handle numbers in variables as character strings like XXX yen

>>> price = 100
>>> 'Price:' + price + 'yen'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only concatenate str (not "int") to str
>>>

• I was angry that I couldn't add (combine) strings and integers.
• Type conversion.

>>> price = 100
>>> 'Price:' + str(price) + 'yen'
'Price:100yen'
>>>

• I was able to handle numbers as strings.

Summary of basics

• Super easy from installation to handling hello world and variables and strings
• I was able to do this in about an hour while taking notes.
• It was something I knew and wrote, but if you do the basics properly, you will learn it.

For Quotations / Lightning Talk

• Knowledge to master
• Persistent knowledge (basic / basic ideas)
• Python is "easy" and "universal", and its drawback is speed, but the interpreter type is a high-speed category.
• A few lines of tool scripts
• Up to large programs