OSX从Pthon 2.7升级到3.8
1，官网下载最新安装包安装
2，执行认证文件command
3，执行设置path command
4，设置默认python
在terminal里运行open ~/.bash_profile，打开~/.bash_profile，直接修改文件保存，重启Terminal。
source ~/.bash_profile
# Setting PATH for Python 3.8
# The original version is saved in .bash_profile.pysave
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/3.8/bin:
alias python="/Library/Frameworks/Python.framework/Versions/3.8/bin/python3.8"
Print练习
>>> print("hello world")
hello world
>>>
>>>
>>> ms="good morning"
>>> print(ms)
good morning
>>>
>>>
>>> ms=
>>> print(ms)
字符串操作
title：首字母大写
upper:全大写
lower:全小写
strip:去掉两头空格
lstrip:去掉左边空格
rstrip:去掉右边空格
+：链接字符串
>>> ms="li xiaobin"
>>>
>>> print(ms.upper())
LI XIAOBIN
>>>
>>> print(ms.lower())
li xiaobin
>>>
>>> print(ms.title())
Li Xiaobin
>>>
>>> ms=" li xiao bin "
>>>
>>> print(ms.strip())
li xiao bin
>>>
>>> print(ms)
li xiao bin
>>> print(ms.lstrip())
li xiao bin
>>>
>>> print(ms.rstrip())
li xiao bin
>>>
>>>
>>> print('li'+ms)
li li xiao bin
>>>
代码注释
# hello world
print("hello ¥n li xiaobin")
如果多行注释可以使用如下方法：
'''
many lines hello world by lixiaobin
'''
print("hello ¥n li xiaobin")