[JSON] How to use jansson lib to generate JSON data in C

This exmple method will generate the result string below:

{ "command":"link_status",
  "result":["AAABBBCCC"] }

char* generate_json_data() { char *ret_strings = NULL; char *ret_string = "AAABBBCCC"; json_t *root = json_object(); json_t *result_json_arr = json_array(); json_object_set_new( root, "command", json_string( "link_status" ) ); json_object_set_new( root, "result", result_json_arr ); ... json_array_append( result_json_arr, json_string( ret_string ) ); free( ret_string ); ret_strings = json_dumps( root, 0 ); json_decref( root ); return ret_strings; }

For more example in details: 

#include <stdio.h> #include <jansson.h> void add_2array_to_json( json_t* obj, const char* name, const int* marr, size_t dim1, size_t dim2 ) { size_t i, j; json_t* jarr1 = json_array(); for( i=0; i<dim1; ++i ) { json_t* jarr2 = json_array(); for( j=0; j<dim2; ++j ) { int val = marr[ i*dim2 + j ]; json_t* jval = json_integer( val ); json_array_append_new( jarr2, jval ); } json_array_append_new( jarr1, jarr2 ); } json_object_set_new( obj, name, jarr1 ); return; } int main() { json_t* jdata; char* s; int arr1[2][3] = { {1,2,3}, {4,5,6} }; int arr2[4][4] = { {1,2,3,4}, {5,6,7,8}, {9,10,11,12}, {13,14,15,16} }; jdata = json_object(); add_2array_to_json( jdata, "arr1", &arr1[0][0], 2, 3 ); add_2array_to_json( jdata, "arr2", &arr2[0][0], 4, 4 ); s = json_dumps( jdata, 0 ); puts( s ); free( s ); json_decref( jdata ); return 0; } When run it outputs: {"arr1": [[1, 2, 3], [4, 5, 6]], "arr2": [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]}

Another example:

#include "jansson.h" ... json_error_t error; json_t *root = json_loads( reply->data.buffer, 0, &error ); if( root ) { json_t *jsonData = json_object_get( root, "data" ); if( json_is_array( jsonData ) ) { const uint length = json_array_size( jsonData ); for( uint i=0; i<length; ++i ) // Iterates over the sequence elements. { json_t *jsonObject = json_array_get( jsonData, i ); json_t *jsonID = json_object_get( jsonObject, "id" ); const char *jsonStringID = json_string_value( jsonID ); json_t *jsonName = json_object_get( jsonObject, "name" ); const char *jsonStringName = json_string_value( jsonName ); // We can now do something with our Name and ID } } json_decref( root ); }