cJSON Back

• cJSON is a c/c++ lib for creating json or parsing json.

Include lib [downloads]

#include "cJSON.h"

1. Create Json Object/Array

cJSON* jobj = cJSON_CreateObject();
cJSON* jarr = cJSON_CreateArray();

2. Add items

/**
 * Object
 */

/** add item to an obj */
cJSON_AddItemToObject(jobj, "arrName", jarr);

/** add string to an obj */
cJSON_AddStringToObject(jobj, "strName", "string");

/** add number to an obj */
cJSON_AddNumberToObject(jobj, "numName", 42);

/**
 * Array
 */

/** add obj to an array */
cJSON_AddItemToArray(jarr, jobj);

• Note: remember to delete after using

    cJSON_Delete(jobj);
    cJSON_Delete(jarr);
  

3. Convert Json Object to a string

char* jsonStr = cJSON_Print(jobj);

• Note: remember to free after using

  free(jsonStr);
  

4. Parse a string to Json Object

cJSON* proot = cJSON_Parse(jsonStr);

5. Get items

/**
 * Object
 */

/** get object item */
cJSON* pobj = cJSON_GetObjectItem(proot, "arrName");
string strValue = cJSON_GetObjectItem(jobj, "strName")->valuestring;
int numValue = cJSON_GetObjectItem(jobj, "numName")->valueint;
double floatValue = cJSON_GetObjectItem(jobj, "numName")->valuedouble;

/**
 * Array
 */

/** get array item i */
cJSON* parr = cJSON_GetArrayItem(jarr, i);

/** get array size */
int arrSize = cJSON_GetArraySize(jarr);