#1. Do not need to complie. [T. But need an interpreter, usually cython.]
#2. Grouping sentences with parentheses. [F. It's space. IndentationError happens without space]
#3. Interpreter ends with end(). [F. exit() or quit()]
#4. Prompt used to input command is called primary prompt. [T]
#5. Default encoding: UTF-8. [T]
#6. Capital character in primary prompt is ">>" [F. ">>>"]
#7. Python string can't be changed. [T. Not just literals, any variables str="***" can't be changed.]
#8. Using """ or ''' (triple quotation) to input multiple lines. [T]
#9. Unable to add a new element to tuples. [T]
#10. Unable to modify keys of dict. [T]
#11. Using items to get tuple from a dict. [T]
#12. "from module import *". [T]
#13. The first detected place of error will be marked by "^". [T]
#14. Exception can be handled with "try" to continue the code. [T]
#15. "Except" will not be processed if there's no exception inside "try". [T]
#16. "Finally" will be processed either exception happens or not. [T]
#17. Are therse all standard lib? gzip,timeit,csv,openpyxl. [F. openpyxl is not.]
#18. Ways to quit interpreter: "ctrl+D" in UNIX; ""ctrl+Z" in windows. [T]
#19. "_" is used to show the last variable. [T]
#20. Can't handle exception happened in except. [T]
#21. Assign multiple exceptions in a single except via tuple. [T]
#22. Mail related standard lib: mailbox, smtplib, poplib [T]
#23. Try to access internet: "from urllib.request import urlopen" [T]
#24. DEBUG < INFO < WARNING < ERROR < CRITICAL
#25.
What's the output:
#1
def job():
pass
job()
#pass does nothing, so there's no output.
#2
num = [1, 2, 3]
del num
print(num)
#NameError
#3
class Greet():
def say(): # need self: say(self)
print('Hello')
sample = Greet()
sample.say()
#TypeError: Greet.say() takes 0 positional arguments but 1 was given
#4
for i in range(5):
print(i)
#IndentationError happens when space is absent before "print(i)"
#5
print(r'C:\sample\number')
#C:\sample\number
#6
str = "a" "a"
#aa
#7
number = 7
def job(arg=number):
print(arg)
number = 10
job()
#7
#8.1
def job(arg, /):
print(arg)
job(arg=5)
#TypeError
#8.2
def job(pos, /, arg, *, kwarg):
print(pos, arg, kwarg)
job(1, arg=2, kwarg=3)
#1,2,3
#Before / can only be pos parameter
#After * can only be keyword parameter
#Between / and * can be both
#9
number = [1, 2, 3]
try:
number.remove(4)
print(number)
except Exception as e:
print(e)
#ValueError:list.remove(x): x not in list
#10
test = 'one',
print(test)
#('one',)
#11
#module.py
def func():
print('hello')
if __name__ == '__main__':
func()
#import module: __name__ <- 'module', so __name__ == '__main__' is false
#python module.py: __name__ <- __main__, so __name__ == '__main__' is true
#12
try:
10 / 0
except (NameError, ValueError):
print('Error')
except Exception as e:
print(e)
#division by zero
#13
try:
print('try')
except:
print('except')
else:
print('else')
finally:
print('finally')
#try
#else
#finally
Usage of python:
#1. Add a new element to a list
from collections import deque
my_list = list() # or my_list = []
my_list.append(1)
my_list.extend([3,4,5])
my_list.insert(1, 2) # Insert 4 at index 1
my_list += [6]
my_list = [*my_list, 7]
#<class 'collections.deque'>
my_list = deque([1, 2, 3])
my_list.append(4) # Adds to the end
my_list.appendleft(0) # Adds to the beginning
#dict can't be appended
#2. Usage of pop() about list and dict
[2,4,1,3,5].pop(2) #It's the order of list
#1
[2:"two",4:"four",1:"one",3:"three",5:"five"].pop(2) #It's the key of dict
#'two'
[2,4,1,3,5].pop() #Pop the last one
#5
{2:"two",4:"four",1:"one",3:"three",5:"five"}.pop()
#TypeError: pop expected at least 1 argument, got 0
#3. Ways to format print()
a = 'Python'
b = 'programing'
print(f'{a} is a {b} language')
print('{0} is a {1} language'.format(a, b))
print('%s is a %s language' % (a, b)
print('{a} is a {b} language'.format(a='a', b='b')) #Wrong
#4. AttributeError
class Item:
Pass
print(Item.name)
#AttributeError: 'Item' object has no attribute 'name'
#5. path.join() for different os
path = os.★★★('C:¥¥', 'dir', 'file.txt')
#This will be handled differently for different os
#"\\" for windows(two "\\" for one "\"), and its output like
#"C:\Users\Username\Documents\MyProject"
#"/" for macOS and linux, and its output like "/home/username/Documents/MyProject"
#Two "\" for one "\" is just because the first "\" is a Escape character which means you can also use "\'" to represent "'".
#6. Ways to copy a file to another folder
import shutil
#Copy without permission, created time and updated time
shutil.copyfile('sample.txt', 'dir/sample.txt')
#Copy with permission only
shutil.copy('sample.txt', 'dir/sample.txt')
#Copy with permission, created time and updated time
shutil.copy2('sample.txt', 'dir/sample.txt')
#7. Way to find the whole file list inside a folder
import glob
title = glob.glob('*.txt')
#8. exit(), quit(), sys.exit(), os._exit()
#quit() and exit() can't be used in production code
#os._exit(): immediate exit
#sys.exit(): sometimes unexpected exception happens, then use sys.exit() in "try...except" sentences.
#9. Virtual environment
#Created a virtual environment in python
python -m venv directory
#Activate a virtual environment in macOS bash
source directory/bin/activate
#10. Commands to start interpreter
python
python[version]
python -c commands [parameters]
#11. r, r+, a
with open('file.txt', '★') as f:
f.write('hello')
#Default: r
#12. Find all packages
#list all packages only
pip list
#list and export all packages
pip freeze > requirements.txt
#13. install, uninstall and upgrade
#install
pip install package
pip install package==2.6.0
#uninstall
pip uninstall package
#upgrade
pip install --upgrade package
pip install -U package
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