cJSON用法

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#include <stdio.h>
#include "cJSON.h"

char* makeJson(void)
{
   cJSON* pJsonRoot = NULL;

   pJsonRoot = cJSON_CreateObject();
   if(NULL == pJsonRoot)
   {
       printf("cJSON_CreateObject failed\n");
       return NULL;
   }
   cJSON_AddStringToObject(pJsonRoot,"hello","hello world");
   cJSON_AddNumberToObject(pJsonRoot,"number",10000);
   cJSON_AddBoolToObject(pJsonRoot,"bool",1);

   cJSON* pSubJson = NULL;
   pSubJson = cJSON_CreateObject();
   if(NULL == pSubJson)
   {
       cJSON_Delete(pJsonRoot);
       return NULL;
   }
   cJSON_AddStringToObject(pSubJson,"subjsonobj","a sub json string");
   cJSON_AddItemToObject(pJsonRoot,"subobj",pSubJson);

   char* p = cJSON_Print(pJsonRoot);
   if(NULL == p)
   {
       cJSON_Delete(pJsonRoot);
       return NULL;
   }
   cJSON_Delete(pJsonRoot);

   return p;
}
void parseJson(char* pMsg)
{
   if(NULL == pMsg)
   {
       return;
   }
   cJSON* pJson = cJSON_Parse(pMsg);
   if(NULL==pJson)
   {
       return ;
   }
   cJSON* pSub = cJSON_GetObjectItem(pJson,"hello");
   if(NULL == pSub)
   {
       printf("GetObjectItem hello failed\n");
       return ;
   }
   printf("obj_1: %s\n",pSub->valuestring);

   pSub = cJSON_GetObjectItem(pJson,"number");
   if(NULL == pSub)
   {
       printf("cJSON_GetObjectItem number failed\n");
       return ;
   }
   printf("obj_2: %d\n",pSub->valueint);

   pSub = cJSON_GetObjectItem(pJson,"bool");
   if(NULL == pSub)
   {
       printf("cJSON_GetObjectItem bool failed\n");
       return ;
   }
   printf("obj_3: %d\n",pSub->valueint);

   pSub = cJSON_GetObjectItem(pJson,"subobj");
   if(NULL == pSub)
   {
       printf("cJSON_GetObjectItem subobj failed\n");
       return ;
   }
   cJSON* pSubSub = cJSON_GetObjectItem(pSub,"subjsonobj");
   if(NULL == pSubSub)
   {
       printf("cJSON_GetObjectItem subjsonobj failed\n");
       return ;
   }
   printf("sub_obj_1: %s\n",pSubSub->valuestring);

   cJSON_Delete(pJson);
}
int main(void)
{
   char* p = makeJson();
   if(NULL == p)
   {
       printf("create json failed\n");
       return -1;
   }
   printf("%s\n",p);

   parseJson(p);
   return 0;

}

输出效果：

gcc -o parsejson parsejson.c cJSON.c cJSON.h -Wall -lm
ljc@ljc:~/test/json/cJSON$ sudo ./parsejson
{
   "hello":   "hello world",
   "number":   10000,
   "bool":   true,
   "subobj":   {
       "subjsonobj":   "a sub json string"
   }
}
obj_1: hello world
obj_2: 10000
obj_3: 1
sub_obj_1: a sub json string

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