Json-c common APIs

What is? Json

​ Json(JavaScript Object Notation,JS Object shorthand ) Is a lightweight data exchange format . Easy to read and write . At the same time, it is also easy for machine analysis and generation .

Some legal Json example ：

Key value pair ：（ You can have no keys, only values ）

	  key        value  
      ↓       ↓
1. {
    "name": "Leo", "sex": "male"}
2. {
    "name": "Jack", "age": 18, "address": {
    "country": "china", "zip-code": "10000"}}
3. {
    "a": "1", "b": [1,2,3]}

Json-c API

json_object Support type ：

/* supported object types */

typedef enum json_type {
    
  /* If you change this, be sure to update json_type_to_name() too */
  json_type_null,
  json_type_boolean,
  json_type_double,
  json_type_int,
  json_type_object,
  json_type_array,
  json_type_string
} json_type;

1. Will conform to Json The format string is constructed as a Json object

   struct json_object * json_tokener_parse(const char *s);
   

2. take Json Object content is converted to Json Format string

   const char *json_object_to_json_string(struct json_object *obj);
   

3. establish Json object

   struct json_object *json_object_new_object();
   

4. Go to Json Object

   void json_object_object_add(struct json_object *obj, const char *key, struct json_object *value);
   

5. take C String conversion to Json Object in string format

   struct json_object* json_object_new_string(const char *s);
   

6. Converts an integer value to Json Formatted objects

   struct json_object* json_object_new_int(int a);
   

7. obtain Json The integer value of the object

   int32 json_object_get_int(struct json_object *obj);
   

8. obtain Json The string value of the object

   const char *json_object_get_string(struct json_object *obj);
   

9. ​ analysis Json Divided into two steps ：

   ​ First step ： By key name , from Json Object to get the corresponding data Json object

   struct json_object *json;
   json_object_object_get_ex(obj, "name", &json);
   

   ​ The second step ： According to the type of data , Set the data to the corresponding Json Object to the corresponding type of data

   json_type type = json_object_get_type(json);
   
   if(json_type_string == type){
         
       printf("name: %s\n". json_object_get_string(json));	//json Object to string type 
   }
   
   // Allied 
   json_object_object_get_ex(obj, "age", &json);
   printf("age: %d\n", json_object_get_int(json));
   
   json_object_object_get_ex(obj, "sex", &json);
   printf("sex: %s\n", json_object_get_string(json));