Windows中Python2与Python3并存,随意切换版本 :
首先需要知道,python默认执行版本由系统环境变量中Python2和Python3的先后顺序决定;
这儿给大家展示在不同情况下利用不同的方法调用python;
#1:Python Launcher调用参数
> py --helpPython Launcher for Windows Version 3.7.150.1013usage:py [launcher-args][python-args] script [script-args]Launcher arguments:-2 : Launch the latest Python 2.x version-3 : Launch the latest Python 3.x version-X.Y : Launch the specified Python version The above all default to 64 bit if a matching 64 bit python is present.-X.Y-32: Launch the specified 32bit Python version-X-32 : Launch the latest 32bit Python X version-X.Y-64: Launch the specified 64bit Python version-X-64 : Launch the latest 64bit Python X version-0 --list : List the available pythons-0p --list-paths : List with paths
py -2 #调用Python2
py -3 #调用Python3
img
程序运行:py -2 *.py
#运行python2程序
py -3 *.py
#运行python3程序
下面是一个python2程序的例子,当使用py -3时,运行失败;
img
#2:修改执行程序.exe名字
..\Python37\python.exe可以修改为python2.exe
..\Python27\python.exe可以修改为python3.exe
这样直接调用python2与python3就不会混乱了;
#3:程序中申明
在python程序首行添加#! python3
指定由python3解释运行;
在python程序首行添加#! python2
指定由python2解释运行;
#3:pip运行
py -2 -m pip install numpy #pip2 install numpy
py -3 -m pip install numpy #pip3 install numpy
#4:Python Launcher for Windows
python launcher是python3.3新增的一个功能,它对所有有的python版本都是兼容的;Python launcher for Windows可以帮助程序或命令选择最合适的python版本作为解释器,而不是最近安装的python版本;安装3.3及更新版本的python时,python launcher默认加入到path中。
详细信息见Python Launcher for Windows
py是python launcher下的一个命令;
##打开最近安装的python版本
> py Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:59:51) [MSC v.1914 64 bit (AMD64)] on win32Type "help", "copyright", "credits" or "license" for more information.
##查看py详细参数
>py -h Python Launcher for Windows Version 3.7.150.1013usage:py [launcher-args][python-args] script [script-args] Launcher arguments:-2 : Launch the latest Python 2.x version -3 : Launch the latest Python 3.x version -X.Y : Launch the specified Python version The above all default to 64 bit if a matching 64 bit python is present. -X.Y-32: Launch the specified 32bit Python version -X-32 : Launch the latest 32bit Python X version -X.Y-64: Launch the specified 64bit Python version -X-64 : Launch the latest 64bit Python X version -0 --list : List the available pythons -0p --list-paths : List with paths The following help text is from Python:usage: C:\Program Files\Python37\python.exe [option] ... [-c cmd | -m mod | file | -][arg] ... Options and arguments (and corresponding environment variables): -b : issue warnings about str(bytes_instance), str(bytearray_instance) and comparing bytes/bytearray with str. (-bb: issue errors) -B : don't write .pyc files on import; also PYTHONDONTWRITEBYTECODE=x -c cmd : program passed in as string (terminates option list) -d : debug output from parser; also PYTHONDEBUG=x -E : ignore PYTHON* environment variables (such as PYTHONPATH) -h : print this help message and exit (also --help) -i : inspect interactively after running script; forces a prompt even if stdin does not appear to be a terminal; also PYTHONINSPECT=x -I : isolate Python from the user's environment (implies -E and -s) -m mod : run library module as a script (terminates option list) -O : remove assert and __debug__-dependent statements; add .opt-1 before .pyc extension; also PYTHONOPTIMIZE=x -OO : do -O changes and also discard docstrings; add .opt-2 before .pyc extension -q : don't print version and copyright messages on interactive startup -s : don't add user site directory to sys.path; also PYTHONNOUSERSITE -S : don't imply 'import site' on initialization -u : force the stdout and stderr streams to be unbuffered; this option has no effect on stdin; also PYTHONUNBUFFERED=x -v : verbose (trace import statements); also PYTHONVERBOSE=x can be supplied multiple times to increase verbosity -V : print the Python version number and exit (also --version) when given twice, print more information about the build -W arg : warning control; arg is action:message:category:module:lineno also PYTHONWARNINGS=arg -x : skip first line of source, allowing use of non-Unix forms of #!cmd -X opt : set implementation-specific option --check-hash-based-pycs always|default|never: control how Python invalidates hash-based .pyc files file : program read from script file : program read from stdin (default; interactive mode if a tty) arg ...: arguments passed to program in sys.argv[1:]
作者:_eason_
链接:https://www.jianshu.com/p/0ca483fd6e0c
共同学习,写下你的评论
评论加载中...
作者其他优质文章