python 字符串对象与编码

s1 = 'abcdefg'

u1 = u'abcdefg'

print s1

print u1

type(s1)

type(u1)

abcdefg

abcdefg

<type 'str'>

<type 'unicode'>

ValueError: Expected a bytes object, not a unicode object

str和unicode互相转换

python内部常用unicode对象处理，比如io.read()方法返回的即为unicode对象，往往需要将其转换为str对象。有时也需要将str转换为unicode对象。仍以上述为例

u2 = s1.decode()

type(u2)

s2 = u1.encode()

type(s2)

<type 'str'>

import io

with io.open('test.html', 'r') as file:
html = file.read()
print type(html)
html = html.encode('utf-8')
print type(html)

<type 'unicode'>

<type 'str'>

“``print`` evaluates each expression in turn and writes the resulting

object to standard output (see below).  If an object is not a string,
it is first converted to a string using the rules for string

conversions.......”

function print(x):

#演示代码仅供理解，实际并非如此

return str(x)

pip install chardet

import chardet

str = 'good'

chardet.detect(str)