首次写博客，勿喷！以后无特殊声明都是在python3.5下操作。

1.python2和python3最基础的差异

1.print

python2和python3在新手看来最大的差别无异乎是print了，我分别演示下：

liukai@bogon:~$ python -V

Python 2.7.10

liukai@bogon:~$ python

Python 2.7.10 (default, Jul 14 2015, 19:46:27)

[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.39)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> a="haha"

>>> print a

haha

>>> print(a)

haha

===========================================

liukai@bogon:~$ python3 -V

Python 3.5.1

liukai@bogon:~$ python3

Python 3.5.1 (default, Jan 8 2016, 23:14:28)

[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.72)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> a="haha"

>>> print(a)

haha

>>> print a

File "<stdin>", line 1

print a

^

SyntaxError: Missing parentheses in call to 'print'

总结：python3只支持print(),python2都支持。

2.input

root@lktest:~# python -V

Python 2.7.11

root@lktest:~# python

Python 2.7.11 (default, Jan 20 2016, 11:58:42)

[GCC 4.4.7 20120313 (Red Hat 4.4.7-16)] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> a=raw_input("input your number: ")

input your number: hello

>>> a

'hello'

>>> b=input("input your number: ")

input your number: hello

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

File "<string>", line 1, in <module>

NameError: name 'hello' is not defined

================================================

root@lktest:~# python3

Python 3.5.1 (default, Jan 3 2016, 03:35:05)

[GCC 4.4.7 20120313 (Red Hat 4.4.7-16)] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> a=raw_input("input your number: ")

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

NameError: name 'raw_input' is not defined

>>> a=input("input your number: ")

input your number: hello

>>> a

'hello'

总结：用户输入函数，python2用raw_input()，python3用input()

2.python基础知识

1.数据类型

1.整型

root@lktest:~# python3

Python 3.5.1 (default, Jan 3 2016, 03:35:05)

[GCC 4.4.7 20120313 (Red Hat 4.4.7-16)] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> a=100

>>> a=-10

>>> a=0

2.浮点型

>>> b=1.23

>>> b=-1.1

>>> b=12.3e8

3.字符串

>>> c="hello"

>>> c="My God"

>>> c="abc\n123"

4.布尔值

>>> d=True

>>> d=False

>>> 6>5

True

>>> 1>4

False

5.空值

空值用None表示，但是None  !=  0

6.变量

>>> e="hello"

>>> f=10

>>> print(e,f)

hello 10

未完待续...