当列表中混合了数字和字符时，python2.x版本中会将字符按照ASCII码转换后进行操作，但是在python3是不会进行转换，因此会导致报错。

一、sort操作

sort 排序元素。 python2中如果元素有数字和字符串，会按照ASCII码来排序，但在Python3中数字和字符串排序会报TypeError错误。

• python 2

# ------------------------------------------------------------------------------------------------------
# Python 2.7.10 (default, Oct 23 2015, 19:19:21) 
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> l1 = ['c','b','d','z',1,3,2,5,3]
>>> l1.sort()
>>> l1
[1, 2, 3, 3, 5, 'b', 'c', 'd', 'z']
# ------------------------------------------------------------------------------------------------------

• python3

# ------------------------------------------------------------------------------------------------------
>>> l1 = ['c','b','d','z',1,3,2,5,3]
>>> l1.sort()
Traceback (most recent call last):
  File "<pyshell#7>", line 1, in <module>
    l1.sort()
TypeError: '<' not supported between instances of 'int' and 'str'
# ------------------------------------------------------------------------------------------------------

二、max操作

max 返回列表中最大的元素，也是存在python3中不能字符串和数字比较的问题。

# ------------------------------------------------------------------------------------------------------
# python3:
>>> max(l1)
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    max(l1)
TypeError: '>' not supported between instances of 'int' and 'str'
>>> max(l2)
34
# 
# -----------------------------------------------------------------------------------------------------
# python2:
>>> l1 = ['a','z',1,3,33]
>>> max(l1)
'z'
# ------------------------------------------------------------------------------------------------------

三、min操作

返回最小元素 min, 同max。

# ------------------------------------------------------------------------------------------------------
# python3
>>> min(l1)
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    min(l1)
TypeError: '>' not supported between instances of 'int' and 'str'
#
# ------------------------------------------------------------------------------------------------------
# python2
>>> min(l1)
1
# ------------------------------------------------------------------------------------------------------