1.文件处理模式b模式
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 # f=open('test.py','rb',encoding='utf-8') #b的方式不能指定编码
4 # f=open('test.py','rb') #b的方式不能指定编码
5 # data=f.read()
6 # #'字符串'---------encode---------》bytes
7 # #bytes---------decode---------》'字符串'
8 # print(data)
9 # print(data.decode('utf-8'))
10 # f.close()
11
12
13 # f=open('test.py','wb') #b的方式不能指定编码
14 # f.write(bytes('1111\n',encoding='utf-8'))
15 # f.write('杨件'.encode('utf-8'))
16
17 # f=open('test.py','ab') #b的方式不能指定编码
18 # f.write('杨件'.encode('utf-8'))
19
20 # open('a;ltxt','wt')
2.读取大文件最后一行
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 f=open('test.txt','rb')
4
5 for i in f:
6 offs=-3
7 n=0
8 while True:
9 f.seek(offs,2)
10 data=f.readlines()
11 if len(data) > 1:
12 print('最后一行',data[-1].decode("utf-8"))
13 break
14 offs*=2
3.文件操作的其他方法
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 # f=open('a.txt','r+',encoding='utf-8')
4 # data=f.read()
5 # print(data)
6 # f.write('你好')
7
8 # f=open('a.txt','r+',encoding='latin-1')
9 # data=f.read()
10 # print(data)
11 # f.write('aaaaaaaaaaa')
12
13 # f=open('a.txt','r',encoding='utf-8',newline='') #读取文件中真正的换行符号
14 f=open('a.txt','r+',encoding='utf-8',newline='') #读取文件中真正的换行符号
15 #
16 # print(f.closed)
17 # print(f.encoding)
18 # f.flush()
19 # print(f.readlines())
20
21 # print(f.tell())
22 # f.readline()
23 # print(f.tell())
24 #
25 # f.seek(1)
26 # print(f.tell())
27 # print(f.readlines())
28 # f.seek(3)
29 # print(f.tell())
30 # print(f.read())
31
32 # data=f.read(1)
33 # print(data)
34
35 f.truncate(10)
36
37
38 # f.flush() #讲文件内容从内存刷到硬盘
39 #
40 # f.closed #文件如果关闭则返回True
41 #
42 # f.encoding #查看使用open打开文件的编码
43 # f.tell() #查看文件处理当前的光标位置
44 #
45 # f.seek(3) #从开头开始算，将光标移动到第三个字节
46 # f.truncate(10) #从开头开始算，将文件只保留从0-10个字节的内容，文件必须以写方式打开，但是w和w+除外
47 #
48 # f=open('a.txt','r',newline='')
49 #
50 # data=f.readline().encode('utf-8')
51 # print(data)
52 # print(f.tell())
53
54
55
56
57
58
59
60 # f=open('seek.txt','r',encoding='utf-8')
61 # print(f.tell())
62 # f.seek(10)
63 # print(f.tell())
64 # f.seek(3)
65 # print(f.tell())
66
67 # f=open('seek.txt','rb')
68 # print(f.tell())
69 # f.seek(10,1)
70 # print(f.tell())
71 # f.seek(3,1)
72 # print(f.tell())
73
74
75 # f=open('seek.txt','rb')
76 # print(f.tell())
77 # f.seek(-5,2)
78 # print(f.read())
79 # print(f.tell())
80 # f.seek(3,1)
81 # print(f.tell())
82
83
84
85
86
87
88
89
90 #
91 # f=open('日志文件.txt','rb')
92 # data=f.readlines()
93 # print(data[-1].decode('utf-8'))
94
95 f=open('日志文件.txt','rb')
96 #
97 # for i in f.readlines():
98 # print(i.decode('utf-8'))
99
100 #循环文件的推荐方式
101 # for i in f:
102 # print(i)
103
104 for i in f:
105 offs=-10
106 while True:
107 f.seek(offs,2)
108 data=f.readlines()
109 if len(data) > 1:
110 print('文件的最后一行是%s' %(data[-1].decode('utf-8')))
111 break
112 offs*=2
4.迭代器和生成器
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3
4
5
6 # x='hello'
7 # # print(dir(x))
8 # iter_test=x.__iter__()
9 # #
10 # print(iter_test)
11 # print(iter_test.__next__())
12 # print(iter_test.__next__())
13 # print(iter_test.__next__())
14 # print(iter_test.__next__())
15 # print(iter_test.__next__())
16 # print(iter_test.__next__())
17
18 # l=[1,2,3]
19 # for i in l: #i_l=l.__iter_() i_l.__next__()
20 # print(i)
21
22 # index=0
23 # while index < len(l):
24 # print(l[index])
25 # index+=1
26
27
28 # iter_l=l.__iter__() #遵循迭代器协议，生成可迭代对象
29 # print(iter_l.__next__())
30 # print(iter_l.__next__())
31 #
32 # for i in l:
33 # print(i)
34
35 # s={1,2,3}
36 #
37 # # for i in s:
38 # # print(i)
39 # iter_s=s.__iter__()
40 # print(iter_s)
41 # print(iter_s.__next__())
42 # print(iter_s.__next__())
43 # print(iter_s.__next__())
44 # print(iter_s.__next__())
45
46 # dic={'a':1,'b':2}
47 # iter_d=dic.__iter__()
48 # print(iter_d.__next__())
49
50 # f=open('test.txt','r+')
51 # # for i in f:
52 # iter_f=f.__iter__()
53 # print(iter_f)
54 # print(iter_f.__next__(),end='')
55 # print(iter_f.__next__(),end='')
56 # l=[1,2,3,4,5]
57 # diedai_l=l.__iter__()
58 # while True:
59 # try:
60 # print(diedai_l.__next__())
61 # except StopIteration:
62 # # print('迭代完毕了,循环终止了')
63 # break
64
65 # l=['die','erzi','sunzi','chongsunzi']
66 # #
67 # iter_l=l.__iter__()
68 # print(iter_l)
69 # print(iter_l.__next__())
70 # print(iter_l.__next__())
71 # print(iter_l.__next__())
72 # print(iter_l.__next__())
73 # print(iter_l.__next__())
74 # print(next(iter_l)) #next()---->iter_l.__next__()
75
76
77
78
79
80
81
82
83
84
85 # def test():
86 # yield 1
87 # yield 2
88 # yield 3
89 # g=test()
90 # print('来自函数',g)
91 # print(g.__next__())
92 # print(g.__next__())
93 # print(g.__next__())
94
95 #三元表达式
96 # name='alex'
97 # # name='linhaifeng'
98 # res='SB' if name == 'alex' else '帅哥'
99 # print(res)
100
101
102 #列表解析
103 # egg_list=[]
104 # for i in range(10):
105 # egg_list.append('鸡蛋%s' %i)
106 # print(egg_list)
107
108 # l=['鸡蛋%s' %i for i in range(10)]
109 # # l1=['鸡蛋%s' %i for i in range(10) if i > 5 ]
110 # # l1=['鸡蛋%s' %i for i in range(10) if i > 5 else i] #没有四元表达式
111 # l2=['鸡蛋%s' %i for i in range(10) if i < 5] #没有四元表达式
112 #
113 # # print(l)
114 # # print(l1)
115 # print(l2)
116
117 # laomuji=('鸡蛋%s' %i for i in range(10)) #生成器表达式
118 # print(laomuji)
119 # print(laomuji.__next__())
120 # print(laomuji.__next__())
121 # print(next(laomuji))
122 # print(next(laomuji))
123 # print(next(laomuji))
124 # print(next(laomuji))
125 # print(next(laomuji))
126 # print(next(laomuji))
127 # print(next(laomuji))
128 # print(next(laomuji))
129 # print(next(laomuji))
130 #
131 l=[1,2,3,34]
132 # map(func,l)
133 #
134 # print(sum(l))
135 # print(sum())
136 print(sum(i for i in range(10000000)))