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#自定义函数，a*a+b*b=c*c，开平方求c值
def Pythagorean_theorem(a,b):
    return 'The right triangle third side\'s length is {}'.format((a**2 + b**2)**(1/2))
#引号内的字符串出现符号时需要使用\转义
#使用.format()将格式化的运算值填入字符串中

#调用函数，传入参数并打印函数返回
print(Pythagorean_theorem(3,4))

PS C:\Users\harveymei> & C:/Users/harveymei/AppData/Local/Programs/Python/Python38/python.exe c:/Users/harveymei/hello.py
The right triangle third side's length is 5.0
PS C:\Users\harveymei> 

#自定义函数，重量克转化为千克
def g2kg(g):
    kg = g / 1000
    return str(kg) + 'kg'

#调用函数并赋值变量
result = g2kg(2500)
#打印变量
print(result)

PS C:\Users\harveymei> & C:/Users/harveymei/AppData/Local/Programs/Python/Python38/python.exe c:/Users/harveymei/hello.py
2.5kg
PS C:\Users\harveymei>

查看系统时间日期配置

[centos@dev ~]$ sudo timedatectl
[sudo] password for centos:
               Local time: Wed 2020-07-01 09:21:55 UTC
           Universal time: Wed 2020-07-01 09:21:55 UTC
                 RTC time: Wed 2020-07-01 09:21:55
                Time zone: UTC (UTC, +0000)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no
[centos@dev ~]$
[centos@dev ~]$ sudo timedatectl --help
timedatectl [OPTIONS...] COMMAND ...

Query or change system time and date settings.

  -h --help                Show this help message
     --version             Show package version
     --no-pager            Do not pipe output into a pager
     --no-ask-password     Do not prompt for password
  -H --host=[USER@]HOST    Operate on remote host
  -M --machine=CONTAINER   Operate on local container
     --adjust-system-clock Adjust system clock when changing local RTC mode
     --monitor             Monitor status of systemd-timesyncd
  -p --property=NAME       Show only properties by this name
  -a --all                 Show all properties, including empty ones
     --value               When showing properties, only print the value

Commands:
  status                   Show current time settings
  show                     Show properties of systemd-timedated
  set-time TIME            Set system time
  set-timezone ZONE        Set system time zone
  list-timezones           Show known time zones
  set-local-rtc BOOL       Control whether RTC is in local time
  set-ntp BOOL             Enable or disable network time synchronization

systemd-timesyncd Commands:
  timesync-status          Show status of systemd-timesyncd
  show-timesync            Show properties of systemd-timesyncd
[centos@dev ~]$

修改系统时区

[centos@dev ~]$ sudo timedatectl set-timezone Asia/Hong_Kong
[centos@dev ~]$ date
Wed Jul  1 17:22:59 HKT 2020
[centos@dev ~]$
[centos@dev ~]$ sudo timedatectl
               Local time: Wed 2020-07-01 17:24:20 HKT
           Universal time: Wed 2020-07-01 09:24:20 UTC
                 RTC time: Wed 2020-07-01 09:24:20
                Time zone: Asia/Hong_Kong (HKT, +0800)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no
[centos@dev ~]$

练习代码1及注释

# -*- coding: utf-8 -*-
print "Hello World!"
print "Hello Again"
print "I like typing this."
print "This is fun."
print 'Yay! Printing.'
print "I'd much rather you 'not'."
print 'I "said" do not touch this.'
# #号用来注释
# 使用Unicode UTF-8编码以避免乱码

练习代码2及注释

# -*- coding: utf-8 -*-
# A comment, this is so you can read your program later.
# Anything after the # is ignored by python.

print "I could have code like this." # and the comment after is ignored

# You can also use a commnet to "disable" or comment out a piece of code:
# print "This won't run."

print "This will run."
# 注释可以是对某行代码的自然语言描述也可以用作临时禁用该行代码
# 注释符的英文名称为octothorepe或者pound character
# 引号中的#号作为字符串中的一个普通字符

练习代码3及注释

# -*- coding: utf-8 -*-
print "I will now count my chickens:"

print "Hens", 25 + 30 / 6
print "Roosters", 100 - 25 * 3 % 4

print "Now I will count the eggs:"

print 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6

print "is it true that 3 + 2 < 5 - 7?"

print 3 + 2 < 5 - 7

print "What is 3 + 2?", 3 + 2
print "What is 5 - 7?", 5 - 7

print "Oh, that's why it's False."

print "How about some more."

print "Is it greater?", 5 > -2
print "Is it greater or equal?", 5 >= -2
print "is it less or equal?", 5 <= -2
# 百分号%表示求余数，75除4得18余3
# 运算优先级为括号，指数，乘，除，加，减
# 1/4运算结果舍去了小数部分