将str文本类型转换为dict

---for test---

1. 往文件写如内容：

   f = open("mall.txt",'w+',encoding='utf-8')
   goods = {
       '电子产品':[
           ['mac',7500,7],
           ['iphone7',5400,5],
           ['thunder',7600,3]
       ],
       '母婴用品':[
           ['帮宝适',45.9,50],
           ['美素佳儿',380,10]
       ],
       '摩托汽车':[
           ['特斯拉',820000,2],
           ['雷克萨斯Rx450',450000,5]
       ],
       '日常用品':[
           ['东北大米',38.5,20],
           ['上海青',3.6,47]
       ]
   }
   s = str(goods)
   f.write(s)
   f.close()

2. 从文件中读取内容：

   with open("mall.txt",'r',encoding="utf-8") as f:
       k = f.read()
       f.close()
   print(k)

3. 如何将读取到的type为str的类dict内容转换回dict类型呢！

　　　　一、用eval函数：

s = eval(k)

print(type(s))
for i in s:
    print(i,s[i])

　　　　二、用json函数：（但是必须注意的是，json格式要求的是双引号，单引号的话会报错【选中单引号 --> ctrl + shift + alt + j  --> 替换单引号为双引号】）

　　　　　　

print(json.loads(goods))

　　　　　　如果是单引号报错内容：

 print(json.loads(k))
  File "F:Python35libjson\__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "F:Python35libjsondecoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "F:Python35libjsondecoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

---恢复内容结束---

for test :

1. 往文件写如内容：

   f = open("mall.txt",'w+',encoding='utf-8')
   goods = {
       '电子产品':[
           ['mac',7500,7],
           ['iphone7',5400,5],
           ['thunder',7600,3]
       ],
       '母婴用品':[
           ['帮宝适',45.9,50],
           ['美素佳儿',380,10]
       ],
       '摩托汽车':[
           ['特斯拉',820000,2],
           ['雷克萨斯Rx450',450000,5]
       ],
       '日常用品':[
           ['东北大米',38.5,20],
           ['上海青',3.6,47]
       ]
   }
   s = str(goods)
   f.write(s)
   f.close()

2. 从文件中读取内容：

   with open("mall.txt",'r',encoding="utf-8") as f:
       k = f.read()
       f.close()
   print(k)

3. 如何将读取到的type为str的类dict内容转换回dict类型呢！

　　　　一、用eval函数：

s = eval(k)

print(type(s))
for i in s:
    print(i,s[i])

　　　　二、用json函数：（但是必须注意的是，json格式要求的是双引号，单引号的话会报错【选中单引号 --> ctrl + shift + alt + j  --> 替换单引号为双引号】）

　　　　　　

print(json.loads(goods))

　　　　　　如果是单引号报错内容：

 print(json.loads(k))
  File "F:Python35libjson\__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "F:Python35libjsondecoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "F:Python35libjsondecoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

---

而字典转成列表就仅仅一个items方法就可以：

> goods = {"apple":2,"ipad pro":18}
> goods.items()
dict_items([('ipad pro', 18), ('apple', 18)])