json-c 0.12 使用介绍

常用函数：

1、json结构体初始化

struct json_object* json_object_new_object() 

2、向json结构体中添加key-value对

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

3、返回json结构体的字符串格式

const char* json_object_to_json_string(struct json_object *obj)

4、基本数据类型转换为json结构体

struct json_object* json_object_new_string(const char *s)

struct json_object* json_object_new_int(int32_t i)

struct json_object* json_object_new_int64(int64_t i)

struct json_object* json_object_new_boolean(json_bool b)

struct json_object* json_object_new_double(double d)

5、json结构体打印

json_object_to_file( jsonfile , json_res );   //打印到文件

printf("%s", json_object_to_json_string(json_res) );  //打印到标准输出

 

          6、 将一个json文件转换成object对象:
                 struct json_object* json_object_from_file(char *filename)
                 举例：  
                     json_object    *pobj = NULL;
                     pobj = json_object_from_file("/home/boy/tmp/test/jsontest/test.json");
     
    7、将json-object写回文件
                    int json_object_to_file(char *filename, struct json_object *obj)
                    举例:
                            json_object_from_file("test.json", pobj);

   8、删除一个对象
                          void json_object_object_del(struct json_object* jso, const char *key);

   9、增加一个对象
                        void json_object_object_add(struct json_object* jso, const char *key, struct json_object *val);
                        举例:
                               json_object_object_add(pobj, "Name", json_object_new_string("Andy"));
                               json_object_object_add(pobj, "Age", json_object_new_int(200));

    10、释放对象
                         void json_object_put(struct json_object *jso);


使用举例
       (1): 新建一个x.json文件
          {
             "item1": "I love JSON",
             "foo": "You love Json",                                                                                                                   
             "item3": "We love JSON",
             "Name": "Andy",
             "Age": 28
          }
       (2):  程序
           
#include   
#include   
#include   
#include   
#include    "json.h"

void  GetValByKey(json_object * jobj, const  char  *sname)
{
    json_object     *pval = NULL;
    enum json_type type;
    pval = json_object_object_get(jobj, sname);
    if(NULL!=pval){
        type = json_object_get_type(pval);
        switch(type)
        {
            case    json_type_string:
                printf("Key:%s  value: %s\n", sname, json_object_get_string(pval));
                break;
            case    json_type_int:
                printf("Key:%s  value: %d\n", sname, json_object_get_int(pval));
                break;
            default:
                break;
        }
    }
}


int  main(void)
{
    json_object    *pobj = NULL;

    //pobj = json_tokener_parse("{ \"abc\": 12, \"foo\": \"bar\", \"bool0\": false, \"bool1\": true, \"arr\": [ 1, 2, 3, null, 5 ] }");

    //printf("new_obj.to_string()=%s\n", json_object_to_json_string(pobj));

    //json_parse(pobj);


    pobj = json_object_from_file("/home/boy/tmp/test/jsontest/test.json");


    GetValByKey(pobj, "foo");

    json_object_object_del(pobj, "foo");
    json_object_object_add(pobj, "foo", json_object_new_string("fark"));
    json_object_object_add(pobj, "Age", json_object_new_int(200));
    GetValByKey(pobj, "Age");
    json_object_to_file("/home/boy/tmp/test/jsontest/new.json", pobj);

    json_object_put(pobj);
    return 0;
}

 

from:

http://blog.sina.com.cn/s/blog_63041bb80101bq24.html

http://kuafu80.blog.163.com/blog/static/12264718020118182915988/