编程小白第一本入门书(三)

一、类

1 class CocaCoca:
2     formula = ['caffeine','sugar','water','soda']    #类的变量（属性）
3 
4 coke_for_me = CocaCoca()    #类的实例化
5 coke_for_you = CocaCoca()
6 
7 print(CocaCoca.formula)     #类属性的引用
8 print(coke_for_me.formula)
9 print(coke_for_you.formula)

类属性与实例属性：

1 class Cocacola:
2     formula = ['caffeine','sugar','water','soda'] #类属性
3 
4 coke_for_China = Cocacola()
5 coke_for_China.local_logo = '可口可乐' #创建实例属性（变量）
6 print(coke_for_China.local_logo)

方法：

1 class Cocacola:
2     formula = ['caffeine','sugar','water','soda'] #类属性
3     def drink(self):   #self就是被创建的实例本身，self=coke
4         print('Energy')
5         
6 coke = Cocacola() #创建实例
7 coke.drink()

 1 class Cocacola:
 2     formula = ['caffeine','sugar','water','soda'] 
 3     def drink(self,how_much):   #其他参数
 4         if how_much == 'a sip':
 5             print('Cool!')
 6         elif how_much == 'whole bottle':
 7             print('Headache')
 8             
 9 ice_coke = Cocacola()
10 ice_coke.drink('a sip')

魔术方法：__init__

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

1 class Cocacola:
2     formula = ['caffeine','sugar','water','soda'] #类属性
3     def __init__(self,logo_name):
4         self.local_logo = logo_name
5     def drink(self):
6         print('Energy')
7 coke = Cocacola('可口可乐')
8 coke.local_logo

二、类的继承

 1 class CocaCola:
 2     calories = 140
 3     sodium = 45
 4     total_carb = 39
 5     caffeine = 34
 6     ingredients = ['High Fructose Corn Syrup',
 7                   'Carbonated Water',
 8                   'Phosphoric Acid',
 9                   'Natural Flavors',
10                   'Caramel Color',
11                   'Caffeine']
12     def __init__(self,logo_name):
13         self.local_logo = logo_name
14     def drink(self):
15         print('You got {} cal energy!'.format(self.calories))

 1 class CaffeineFree(CocaCola):    #CaffeineFree为子类，CocaCola为父类
 2     caffeine = 0
 3     ingredients =['High Fructose Corn Syrup',
 4                  'Carbonated Water',
 5                  'Phosphoric Acid',
 6                  'Natural Flavors',
 7                  'Caramel Color',
 8                  ]
 9 coke_a = CaffeineFree('Cocacola-FREE')
10 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 "\n" 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 "\n" 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：

 1 txt = 'C:/Users/LKX/Desktop/runoob.txt'
 2 with open(txt,'r') as f:
 3     print(f.read())
 4     print('*'*20)
 5 with open(txt,'r') as f:
 6     print(f.readline())
 7     print(f.readline(5)) #指定字节数
 8     print(f.readline())
 9     print('*'*20)
10 with open(txt,'r') as f:
11     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\n', ' 2:www.runoob.com\n', ' 3:www.runoob.com\n', ' 4:www.runoob.com\n', ' 5:www.runoob.com']