python怎样把字符串变成字典【Python教程】,python怎么把字符串变成字典

比方字符串：

user_info = '{"name" : "john", "gender" : "male", "age": 28}'

我们想把它转为下面的字典：

user_dict = {"name" : "john", "gender" : "male", "age": 28}

有以下几种要领：

1、经由过程json来转

>>> import json
>>> user_info= '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = json.loads(user_info)
>>> user_dict
{u'gender': u'male', u'age': 28, u'name': u'john'}

然则运用json举行转换存在一个潜伏的题目。

由json语法划定数组或对象当中的字符串必需运用双引号，不能运用单引号 (官网上有一段形貌是 “A string is a sequence of zero or more Unicode characters, wrapped in double quotes, using backslash escapes” )。因而下面的转换是毛病的：

>>> import json
>>> user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
# 因为字符串运用单引号，会致使运转失足
>>> user_dict = json.loads(user_info)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 380, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 1 column 2 (char 1)

2、经由过程eval

>>> user_info = '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = eval(user_info)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}
>>> user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
>>> user_dict = eval(user_info)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}

经由过程eval举行转换就不存在上面运用json举行转换的题目。然则，运用eval却存在平安性的题目。

3、经由过程 literal_eval

>>> import ast
>>> user = '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = ast.literal_eval(user)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}
user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
>>> user_dict = ast.literal_eval(user)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}

运用ast.literal_eval举行转换既不存在运用json举行转换的题目，也不存在运用 eval 举行转换的平安性题目，因而引荐运用ast.literal_eval。

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