Python2中的​​print​​是一个语句,而Python3中是一个函数

Python2代码 ​​example.py​

def greet(name):
print "Hello, {0}!".format(name)
print "What's your name?"
name = raw_input()
greet(name)

命令行中执行指令

$ 2to3 -w example.py

Python3代码

def greet(name):
print("Hello, {0}!".format(name))
print("What's your name?")
name = input()
greet(name)

书写兼容代码

from __future__ import print_function


参考:
​https://docs.python.org/2/library/2to3.html​​​​