Python 3版本较之前版本语法的一些改动搜集

市面上的Python教程基本都是以3.0以下版本来讲解的，python 从3.0之后一些语法都做了写更改，有时候可能会浪费比较多的时间，记录下使用过程中遇到的情况以备后查。

1、Print (1)需要加括号 (2)打印文件重定向

(1)print ('hello world!!')

(2) print([object, ...], *, sep=' ', end='\n', file=sys.stdout)

log = open('test.txt','a')
print (1,2,3, file=log, end='\n')
print (4,5,6, file=log, end='\n')
log.close()
print (7,8,9)

 2、commands modle 在3.0之后使用subprocess来代替。

Deprecated since version 2.6: The commands module has been removed in Python 3.0. Use the subprocess module instead.

>>> import commands
>>> commands.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> commands.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> commands.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
>>> commands.getoutput('ls /bin/ls')
'/bin/ls'
>>> commands.getstatus('/bin/ls')
'-rwxr-xr-x  1 root        13352 Oct 14  1994 /bin/ls'

>>> import subprocess
>>> subprocess.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> subprocess.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> subprocess.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
>>> subprocess.getoutput('ls /bin/ls')
'/bin/ls'

 3. input 替代raw_input

raw_input
Converts raw_input() to input().

while True:
    reply = input('Enter Text:')
    if reply == 'stop': break
    print (reply.upper())