Arduino Strings

Projects Programming
9

I am using Arduino UNO

Nothing seems to be working!!!

#include <SPI.h>
#include <RH_RF95.h>
#include <ArduinoJson.h>


void setup() {
   Serial.begin(9600);
  while (!Serial) ; // Wait for serial port to be available

}

void loop() {
  String x = "aaaa";
  String fin = "{\"dv\" : \"dfv\", \"FFFF\":\" " +x +"\", \"131\": \"23413241\"} ";
  Serial.println(fin);
  delay(1000);

}

Here is a piece of code that works fine! i used c_str() but nothing!
I need the string format to parse it in ArduinoJson butarray formt to send the data via arduino dragino! (Sorry for the cross post)