Name and use

Naming error handling

variable name is label

Modify string case

Using variables in strings

Format string

Insert newlines and tabs into strings

Remove trailing spaces

integer

float

constant

Comments are text in the code that are not executed and are part of the code

Good comments can enhance the readability of your code

For text starting with '#', the entire line will be treated as a comment and will be ignored during execution.

list = [elem1,elem2,...,]

list[i]

family = ["abs","ppo","pva","pe"]; message = "The First Ploymer is {}".format(family[0].upper()); print(message);

Add element

Modify elements

Delete element

Organization list

for x in list:

#!/usr/bin/python3 animals = ["dog","cat","fish","goat","ox","giraffe","guoqing"]; for animals in animals: print(f"The animal is {animal.title()}"); print(f"Think you ,{animal.upper()}",end = ' '); print("That is all!!");

range(start,stop,step)

max(), min(), sum()

numbers = [value**3 for value in range(0,50,2)]; print(numbers);

One line of statements completes multiple steps

slip

copy

tuple_name = (elem1,elem2,elem3,...)

Modify tuple

Modify elements in a tuple

if A == B: function1(); elif A == C: function2(): else: exit();

if A in B: function(A); else: exit();

if condition == True: actions();

if condition == True: action1(); else: action2();

if condition1: action1(); elif condition2: action2(); ..... else: default_action();

for element in list: if element == condition: action1(); else: action2();

if list: print("NOT EMPTY"); else: print("EMPTY");

dictionary = { key1:value1,key2,value2,...}

dictionary = {}

value = dictionary[key]

dictionary[key3] = value3

del dictionary[key]

.get(key,default_value)

.items()

.keys()

.values()

dictionary list

list dictionary

dictionary dictionary

set(dictionary)

They are all defined by {```}

Collections have no order

The elements in the set are not repeated

get_input = input("prompt")

Can only accept strings and output strings

You can use other functions to convert strings

num = int(input("please input a number ")); if num == 0: print("{} is multiple of 10.".format(num)); else: print(f"{num} is not multiple of 10.");

i = 0; while i < 5 : print(i); i = i 1;

message = ""; while message != "quit": print(message); message = input("please input a phrase and I will repeat it ");

flag = True; message = "" while flag == True: message = input(""); if message == "quit": flag = False; else: print(message);

break

continue

list = ["elem1","elem2","elem3","elem1","elem2"]; while "elem1" in list: list.remove("elem1");

active_flag = True; response = {}; while active_flag == True: name = input("what\'s your name?"); response[name] = input("what\'s your hobby?"); if input("would you like let another person respond?") == "no": active_flag = False; for n,h in response.items(): print("{}\'s hobby is {} ".format(n,h));

positional argument

Keyword arguments

Default values ​​for function parameters

Omitable function parameters

Return simple parameters

Return dictionary

Pass a copy of the list

Pass the entire list

def fun(in,*params)

* means constructing a tuple from all the remaining parameters passed in

def build(first,second,**etc)

** means constructing a dictionary from the remaining key-value pairs

build("Yasin","Jue",sex="m",weight=120);

Save the function as a file with the .py suffix

Import functions and modules

Use aliases for functions and modules

Edamame is a dog, and dog is a category, or category for short.

A type of things often have common attributes, for example, a dog has four legs (attributes), a dog can bark (methods), etc.

Abstracting specific things is called the attributes and methods of a class.

class dog: '''This is a dog''' def __init__(self,name,age): self.name = name; self.age = age; self.legs = 4; def bark(self): print("woof woof woof~"); maodou = dog("MaoDou",5); maodou.bark(); print(maodou.age);

Dog is a big category, which is also subdivided into subcategories such as Pomeranian, Teddy, Husky, Chuanchuan and so on.

Edamame is Chuanchuan, and Chuanchuan is also a type of dog, so Chuanchuan also has the basic characteristics of a dog.

Chuanchuan is a subclass of dog, and dog is the parent class of Chuanchuan.

class Dog: def __init__(self,age=1,name=""): self.age = age; self.name = name; self.legs = 4; def bark(self): print(f"{self.name}:wowowwo~!"); def sit(self): print(f"{self.name}:sit down"); def set_age(self,new_age=0): self.age = new_age; def set_name(self,new_name=""): self.name = new_name; class ChuanChuan(Dog): def __init__(self,father="keji",mother="lachang",age=1,name=""): super().__init__(age,name); self.father = father; self.mother = mother; def set_father(self,father_name=""): self.father = father_name; def set_mother(self,mother_name=""): self.mother = mother_name; add_active = True; dogs = [] #What is added to the list is the address. Putting it here will cause a logic error. #temp_dog = ChuanChuan(); while add_active == True: temp_dog = ChuanChuan(); temp_dog.set_name(input("Please input your dog\'s name: ")); temp_dog.set_age(int(input("Please input your dog\'s age: "))); temp_dog.set_father(input("Please input your dog\'s father: ")); temp_dog.set_mother(input("Please input your dog\'s mother: ")); dogs.append(temp_dog); if "no" == input("Would you want to add another dog? "): add_active = False; else: print(' '); for i in dogs: print(f"name:{i.name} age:{i.age} father:{i.father} mother:{i.mother}");

Use alias

import

with open("file_name.tail") as file_object: contents = file_object.read()

with

open()

.close()

Read full text

read line by line

open() mode

SRC_FILE = "test.py" DEST_FILE = "test.txt" with open(SRC_FILE) as source_file: with open(DEST_FILE,'w') as destin_file: destin_file.write(source_file.read());

.split()

.count("keyword")

try: action(); except ErrorInfo: deal_with_errpr(); else: go_on_without_error();

Error type

Silently fails

#-*- encoding: UTF-8 -*- def count_word(*file_name): word_num = []; for f in file_name: tmp_txt = ""; try: with open(f,'r',encoding='utf-8') as cur_file: tmp_text = cur_file.read(); except FileNotFoundError: print(f"Sorry,the file {f} does not exist."); word_num.append(-1); pass else: word_num.append(len(tmp_text.split())); return word_num; word_in_file = count_word("test.py","copy_list.py","test.text","test_module.py","non.file"); print(word_in_file);

JSON

import json file_name = "setting.json" user_info = {}; user_info["name"] = input("please input your name "); user_info["age"] = int(input("please input your age ")); user_info["phone"] = input("please input your phone "); try: with open(file_name,'w') as f: for i in user_info.values(): json.dump(i,f); except FileNotFoundError: pass

Important behaviors for your code

Consider again when the project is widely used

import unittest def get_formatted_name(first,last): return (first ' ' last).title(); class NameTestCase(unittest.TestCase): '''Test function functionality''' def test_first_last_name(self): format_name = get_formatted_name("yasin","jue"); self.assertEqual(format_name,"Yasin Jue"); if __name__ == "__main__": unittest.main();

assertion method

import unittest class Survey: def __init__(self,name="",questions=""): self.name = name; self.questions = questions; self.responses = []; def get_usr_name(self): self.name = input("What\'s your name? "); def store_response(self,new_resp=""): self.response.append(new_resp); def start_survey(self): for q in self.questions: response = input(q ' '); self.store_response(response); def show_result(self): for q,w in self.questions,self.responses: print(f"Question:{q}\tAnswer:{w} "); class TestSurveyClass(unittest.TestCase): def test_get_usr_name(self): usr_name = "test pony"; pony = Survey(usr_name,"test"); self.assertTrue(pony.name == "test pony"); def test_call_pony_again(self): self.assertEqual(pony.questions,"test"); unittest.main();

.setUp()