编程小白第一本入门书(三)

一、类

class CocaCoca:
    formula = ['caffeine','sugar','water','soda']    #类的变量（属性）

coke_for_me = CocaCoca()    #类的实例化
coke_for_you = CocaCoca()

print(CocaCoca.formula)     #类属性的引用
print(coke_for_me.formula)
print(coke_for_you.formula)

类属性与实例属性：

class Cocacola:
    formula = ['caffeine','sugar','water','soda'] #类属性

coke_for_China = Cocacola()
coke_for_China.local_logo = '可口可乐' #创建实例属性（变量）
print(coke_for_China.local_logo)

方法：

class Cocacola:
    formula = ['caffeine','sugar','water','soda'] #类属性
    def drink(self):   #self就是被创建的实例本身，self=coke
        print('Energy')
        
coke = Cocacola() #创建实例
coke.drink()

class Cocacola:
    formula = ['caffeine','sugar','water','soda'] 
    def drink(self,how_much):   #其他参数
        if how_much == 'a sip':
            print('Cool!')
        elif how_much == 'whole bottle':
            print('Headache')
            
ice_coke = Cocacola()
ice_coke.drink('a sip')

魔术方法：__init__

class Cocacola:
    formula = ['caffeine','sugar','water','soda'] #类属性
    def __init__(self):    #创建实例时自动执行
        self.local_logo = '可口可乐'
    def drink(self):
        print('Energy')
coke = Cocacola()
print(coke.local_logo)

class Cocacola:
    formula = ['caffeine','sugar','water','soda'] #类属性
    def __init__(self,logo_name):
        self.local_logo = logo_name
    def drink(self):
        print('Energy')
coke = Cocacola('可口可乐')
coke.local_logo

二、类的继承

class CocaCola:
    calories = 140
    sodium = 45
    total_carb = 39
    caffeine = 34
    ingredients = ['High Fructose Corn Syrup',
                  'Carbonated Water',
                  'Phosphoric Acid',
                  'Natural Flavors',
                  'Caramel Color',
                  'Caffeine']
    def __init__(self,logo_name):
        self.local_logo = logo_name
    def drink(self):
        print('You got {} cal energy!'.format(self.calories))

class CaffeineFree(CocaCola):    #CaffeineFree为子类，CocaCola为父类
    caffeine = 0
    ingredients =['High Fructose Corn Syrup',
                 'Carbonated Water',
                 'Phosphoric Acid',
                 'Natural Flavors',
                 'Caramel Color',
                 ]
coke_a = CaffeineFree('Cocacola-FREE')
coke_a.drink()

You got 140 cal energy!

三、填充用户假数据

1.readline()方法、readlines()方法：

readline() 方法用于从文件读取整行，包括 " " 字符。如果指定了一个非负数的参数，则返回指定大小的字节数，包括 " " 字符。

readlines() 方法用于读取所有行(直到结束符 EOF)并返回列表，该列表可以由 Python 的 for... in ... 结构进行处理。返回列表，包含所有的行。

文本每一行前有一个空格：

txt = 'C:/Users/LKX/Desktop/runoob.txt'
with open(txt,'r') as f:
    print(f.read())
    print('*'*20)
with open(txt,'r') as f:
    print(f.readline())
    print(f.readline(5)) #指定字节数
    print(f.readline())
    print('*'*20)
with open(txt,'r') as f:
    print(f.readlines())

 1:www.runoob.com
 2:www.runoob.com
 3:www.runoob.com
 4:www.runoob.com
 5:www.runoob.com
********************
 1:www.runoob.com

 2:ww
w.runoob.com

********************
[' 1:www.runoob.com
', ' 2:www.runoob.com
', ' 3:www.runoob.com
', ' 4:www.runoob.com
', ' 5:www.runoob.com']