循环loop

　　有限循环，次数限制

　　无限循环=死循环

for

 

编写登陆接口

输入用户名密码

认证成功后显示欢迎信息

错误三次后锁定

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

_user = "smoke"
_passwd = "smoke520"

username = input("Username:")
password = input("Password:")

if username == _user and password == _passwd:
    print("Welcome %s login..." % _user)
else:
    print("Invalid username or password!")

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
Username:smoke1
Password:skkdk
Invalid username or password!

Process finished with exit code 0

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

_user = "smoke"
_passwd = "smoke520"

username = input("Username:")
password = input("Password:")

if username == _user and password == _passwd:
    print("Welcome %s login..." % _user)
else:
    print("Invalid username or password!")
    
username = input("Username:")    #代码重复
password = input("Password:")

if username == _user and password == _passwd:
    print("Welcome %s login..." % _user)
else:
    print("Invalid username or password!")

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
Username:smoke1
Password:smoke
Invalid username or password!
Username:smoke2
Password:smoke
Invalid username or password!

Process finished with exit code 0

有限循环

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(3):
    print(i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
0
1
2

Process finished with exit code 0

range()

python2.x

[root@node1 ~]# python2
Python 2.7.5 (default, Apr 11 2018, 07:36:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> range(3)
[0, 1, 2]

有限循环

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(3):
    print("loop:",i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
loop: 0
loop: 1
loop: 2

Process finished with exit code 0

range()

python2.x

[root@node1 ~]# python2
Python 2.7.5 (default, Apr 11 2018, 07:36:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> range(1,3)
[1, 2]
>>> range(1,4)
[1, 2, 3]
>>> range(2,4)
[2, 3]
>>> range(2,5)
[2, 3, 4]

有限循环

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(1,4):
    print("loop:",i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
loop: 1
loop: 2
loop: 3

Process finished with exit code 0

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(1,101):
    print("loop:",i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
loop: 1
loop: 2
loop: 3
loop: 4
loop: 5
loop: 6
loop: 7
loop: 8
loop: 9
loop: 10
loop: 11
loop: 12
loop: 13
loop: 14
loop: 15
loop: 16
loop: 17
loop: 18
loop: 19
loop: 20
loop: 21
loop: 22
loop: 23
loop: 24
loop: 25
loop: 26
loop: 27
loop: 28
loop: 29
loop: 30
loop: 31
loop: 32
loop: 33
loop: 34
loop: 35
loop: 36
loop: 37
loop: 38
loop: 39
loop: 40
loop: 41
loop: 42
loop: 43
loop: 44
loop: 45
loop: 46
loop: 47
loop: 48
loop: 49
loop: 50
loop: 51
loop: 52
loop: 53
loop: 54
loop: 55
loop: 56
loop: 57
loop: 58
loop: 59
loop: 60
loop: 61
loop: 62
loop: 63
loop: 64
loop: 65
loop: 66
loop: 67
loop: 68
loop: 69
loop: 70
loop: 71
loop: 72
loop: 73
loop: 74
loop: 75
loop: 76
loop: 77
loop: 78
loop: 79
loop: 80
loop: 81
loop: 82
loop: 83
loop: 84
loop: 85
loop: 86
loop: 87
loop: 88
loop: 89
loop: 90
loop: 91
loop: 92
loop: 93
loop: 94
loop: 95
loop: 96
loop: 97
loop: 98
loop: 99
loop: 100

Process finished with exit code 0

取余

python2.x

[root@node1 ~]# python2
Python 2.7.5 (default, Apr 11 2018, 07:36:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 10 % 2
0
>>> 10 % 3
1
>>> 10 % 4
2
>>> 10 % 5
0
>>> 10 % 6
4
>>> 5 % 2
1
>>> 1 % 2
1
>>> 2 % 2
0
>>> 3 % 2
1
>>> 4 % 2
0
>>> 5 % 2
1

有限循环

打印1-100奇数

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(1,101):
    if i % 2 == 1:
        print("loop:",i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
loop: 1
loop: 3
loop: 5
loop: 7
loop: 9
loop: 11
loop: 13
loop: 15
loop: 17
loop: 19
loop: 21
loop: 23
loop: 25
loop: 27
loop: 29
loop: 31
loop: 33
loop: 35
loop: 37
loop: 39
loop: 41
loop: 43
loop: 45
loop: 47
loop: 49
loop: 51
loop: 53
loop: 55
loop: 57
loop: 59
loop: 61
loop: 63
loop: 65
loop: 67
loop: 69
loop: 71
loop: 73
loop: 75
loop: 77
loop: 79
loop: 81
loop: 83
loop: 85
loop: 87
loop: 89
loop: 91
loop: 93
loop: 95
loop: 97
loop: 99

Process finished with exit code 0

有限循环

打印1-100奇数

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(1,101,2):    #步长
    print("loop:",i)


/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
loop: 1
loop: 3
loop: 5
loop: 7
loop: 9
loop: 11
loop: 13
loop: 15
loop: 17
loop: 19
loop: 21
loop: 23
loop: 25
loop: 27
loop: 29
loop: 31
loop: 33
loop: 35
loop: 37
loop: 39
loop: 41
loop: 43
loop: 45
loop: 47
loop: 49
loop: 51
loop: 53
loop: 55
loop: 57
loop: 59
loop: 61
loop: 63
loop: 65
loop: 67
loop: 69
loop: 71
loop: 73
loop: 75
loop: 77
loop: 79
loop: 81
loop: 83
loop: 85
loop: 87
loop: 89
loop: 91
loop: 93
loop: 95
loop: 97
loop: 99

Process finished with exit code 0

range()

python2.x

[root@node1 ~]# python2
Python 2.7.5 (default, Apr 11 2018, 07:36:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> range(1,101,2)    #2 步长
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99]

有限循环

循环1-100,50-70不打印

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

for i in range(100):
    if i < 50 or i > 70:
        print(i)

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99

Process finished with exit code 0

编写登陆接口

输入用户名密码

认证成功后显示欢迎信息

错误三次后锁定

#!/usr/bin/env python3.8
# __author: "smoke"
# date: 2020/11/23 下午8:57

_user = "smoke"
_passwd = "smoke520"

for i in range(3):
    username = input("Username:")
    password = input("Password:")

    if username == _user and password == _passwd:
        print("Welcome %s login..." % _user)
    else:
        print("Invalid username or password!")

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
Username:smoke
Password:smoke
Invalid username or password!
Username:smoke
Password:smoke520    #对了还打印
Welcome smoke login...
Username:smoke
Password:smoke1
Invalid username or password!

Process finished with exit code 0

break

_user = "smoke"
_passwd = "smoke520"

for i in range(3):
    username = input("Username:")
    password = input("Password:")

    if username == _user and password == _passwd:
        print("Welcome %s login..." % _user)
        break   #跳出，中断
    else:
        print("Invalid username or password!")

/home/smoke/PycharmProjects/pythonProject/venv/bin/python /home/smoke/PycharmProjects/pythonProject/lean_python/login.py
Username:smoke
Password:smoke
Invalid username or password!
Username:smoke
Password:smoke520
Welcome smoke login...

Process finished with exit code 0