python零基础入门到实战，基础知识总结（二）

33 类

class Dog():
    def __init__(self,name,age):
        self.name =name
        self.age = age

    def sit(self):
        print(self.name+''+self.age)

dog = Dog('jeety',24)
print(dog.name)

34 类 汽车里程表

class Car():
    def __init__(self,make,model,year):
        self.make = make
        self.model = model
        self.year = year

    def getCarName(self):
        print(self.model)

car = Car('audi','ad4',2016)
print(car.make)

35 子类方法 init ()

class Car():
    def __init__(self,name):
        self.name = name

class Elastic(Car):
    def __init__(self, name):
        super().__init__(name)

myTesla = Elastic('tesla')
print(myTesla.name)

36 class实例

class Car():
    def __init__(self,make,name,color):
        self.make = make
        self.name = name
        self.color  = color

    def getCarName(self):
        print('获取车的名字为'+self.name+'获取汽车的颜色'+self.color)

class Batery():
    def __init__(self,batery='60'):
        self.batery = batery

    def discribe_batery(self):
        print('This car has'+str(self.batery)+'batery')

class Elatrity(Batery):
    def __init__(self, batery):
        super().__init__(batery)
        self.batery = Batery()

elatrity = Elatrity('100')
print(elatrity.discribe_batery())

37 文件和异常

f = open('file.txt',mode="w",encoding='utf-8')
print(f)
f.write('叫我詹躲躲\n')
f.write('叫我詹躲躲1\n')
f.close()

38 将数据存入json文件

import json
numbers = [1,2,23,3,4,5,6,7,87]

filename = 'numbers.json'
with open(filename,'w') as f_obj:
    json.dump(numbers,f_obj)

39 保存和读取用户生成的数据

import json
username = input('存储输入的数据')

filename = 'numbers.json'
with open(filename,'w') as f_obj:
    json.dump(username,f_obj)

40 读取用户输入的信息

在这里插入代码片import json
filename = 'numbers.json'
with open(filename) as f_obj:
    username = json.load(f_obj)
    print('Welcome back',username)

41 输入和合并数据

import json
filename = 'numbers.json'
try:
    with open(filename) as f_obj:
        username = json.load(f_obj)
except FileNotFoundError:
    username = input('存储输入的数据')
    with open(filename,'w') as f_obj:
        json.dump(username,f_obj)
else:
    print('Welcome back',username)

42 封装成为一个函数

import json
def get_username():
    filename = 'numbers.json'
    try:
        with open(filename) as f_obj:
            username = json.load(f_obj)
    except FileNotFoundError:
        return None
    else:
        return username
def get_greeting():
    username = get_username()
    if username:
       print('Welcome back',username)
    else:
        username = input('存储输入的数据')
        filename = 'numbers.json'
        with open(filename,'w') as f_obj:
            json.dump(username,f_obj)
            print('Welcome back',username)

get_greeting()  

43 文件读取

f = open('index.txt',encoding='utf-8')
s = f.read()
print(s)
f.close()

44 文件写入

f = open('index.txt',mode="w",encoding='utf-8')
f.write('叫我詹躲躲n')
f.write('叫我詹躲躲1n')
f.close()

45 第三方库安装和使用

import random
random.randint() #随机数
import jieba #结巴
import wordcloud #词云

jieba.lcut('分割中文词语的序列')  #分割中文词语的序列
word_cloud = wordCloud(font_path='msyh.ttc').generate('分割中文词语') #生成词云对象
word_cloud.to_file('123.png') #保存到图片

46 python 里面的类和对象

#面向对象编程
class Person:
 def __init__(self,name,sex,birthday):
 self.name = name
 self.sex = sex
 self.birthday = birthday
 def say(self,word):
 print(f'{self.name}说："{word}"')

zhang_san = Person('张三','男','2020202')
zhang_san.say('12121')

47.输出 %占位符

lastname = 'hello'
firstname = 'world'
print('我的名字是%s %s' %(lastname,firstname))

48.常用的格式化字符

%c #字符
%s #通过str来格式化
%i #有符号十进制整数
%d #有符号十进制整数
%u #无符号十进制整数
%o #八进制整数
%x #十六进制整数（小写字母）
%e #索引符号（小写e)
%E #索引符号（大写E)
%f #浮点实数
%g #%f和%e的简写
%G #%f和%E的简写

49格式化的其他方式 format

name = '老夫子'
age = 28
print('姓名:{},年龄{}'.format(name,age))
#姓名:老夫子,年龄28

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