In-depth understanding of Python introduction, basic syntax, and process control

1. User input

#!/usr/bin/env python
#_*_coding:utf-8_*_
#name = raw_input("What is your name?") #only on python 2.x
name = input("What is your name?")
print("Hello " + name )

2. When entering the password, if you want it to be invisible, you need to use the getpass method in the getpass module, that is:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import getpass
# 将用户输入的内容赋值给 name 变量
pwd = getpass.getpass("请输入密码：")
# 打印输入的内容
print(pwd)

3. sys module

#!/usr/bin/env python
# -*- coding: utf-8 -*- 
import sys
print(sys.argv)

#Output

$ python test.py helo world
['test.py', 'helo', 'world']  #把执行脚本时传递的参数获取到了

4, os module

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import os
os.system("df -h") #调用系统命令

import os,sys
os.system(''.join(sys.argv[1:])) #把用户的输入的参数当作一条命令交给os.system来执行

5, if statement

场景一、用户登陆验证
# 提示输入用户名和密码
# 验证用户名和密码
#     如果错误，则输出用户名或密码错误
#     如果成功，则输出 欢迎，XXX!
  
  
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import getpass
name = raw_input('请输入用户名：')
pwd = getpass.getpass('请输入密码：')
if name == "alex" and pwd == "cmd":
    print("欢迎，alex！")
else:
    print("用户名和密码错误")

6, expression for loop

is the simplest Loop 10 times

#!/usr/bin/env python
#_*_coding:utf-8_*_
__author__ = 'Alex Li'
for i in range(10):
    print("loop:", i )

7, while loop 　

count = 0
while True:
    print("你是风儿我是沙,缠缠绵绵到天涯...",count)
    count +=1

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