iothub_client_device_twin_and_methods_sample.c

...

//char* reportedProperties = serializeToJson(&car);
char reportedProperties[512];
sprintf(reportedProperties, "{\"temperature\": 27.6, \"humidity\": 67.3}");

if (reportedProperties != NULL)
{
        (void)IoTHubDeviceClient_LL_SendReportedState(iotHubClientHandle, (const unsigned char*)reportedProperties, strlen(reportedProperties), reportedStateCallback, NULL);
        (void)IoTHubDeviceClient_LL_SetDeviceMethodCallback(iotHubClientHandle, deviceMethodCallback, NULL);
        (void)IoTHubDeviceClient_LL_SetDeviceTwinCallback(iotHubClientHandle, deviceTwinCallback, &car);

...