for循环与if配合使用的简单例子

先上代码：

#!/usr/bin/env python
import getpass

flag = True
for i in range(3):
    user = input("Please input your username:")
    #采用getpass在接收输入的时候不会显示密码,but somehow getpass在pycharm里使用会出问题，需要在cmd里运行
    passwd = getpass.getpass('Please input your password:')
    print(type(passwd))
    passwd = int(passwd)
    print(type(passwd))

    if user == 'Richard'and passwd == 123:
        print('{0} login successfully.'.format(user))
        flag = False
        break
    else:
        print("Invalid username or password.")
if flag:
    print("Wrong input more than 3 times. Program exit.")

运行结果：

E:\python 14>python day0102.py
Please input your username:Richard
Please input your password:
<class 'str'>
<class 'int'>
Richard login successfully.

 另外顺便在这里提一下range的用法：

for i in range(10):
    print(i)
print('---------------------------')
for i in range(0,10,2):
    print(i)

运行结果：

D:\Python\Python36\python.exe "E:/python 14/day0102.py"
0
1
2
3
4
5
6
7
8
9
---------------------------
0
2
4
6
8