//network time
  #include <ESP32Time.h>
ESP32Time rtc;
String TimeStamp = "";

void setup() {
  // put your setup code here, to run once:
    Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
    //TimeStamp = String(rtc.getYear()) + "-" + String(rtc.getMonth())  + "-" + String(rtc.getDay())  + " " + String(rtc.getHour(true))  + ":" + String(rtc.getMinute()) + ":" + String(rtc.getSecond());
    //TimeStamp = getTimeStamp();
    TimeStamp = rtc.getDate() + " " +rtc.getTime();//getTimeStamp();

    Serial.println(TimeStamp.c_str());
    delay(1000);
}

String getTimeStamp(){
  char buffer [20];  
  TimeStamp = String(sprintf(buffer, "%04d-%02d-%02d %02d:%02d:%02d", String(rtc.getYear()), String(rtc.getMonth()), String(rtc.getDay()), String(rtc.getHour(true)), String(rtc.getMinute()), String(rtc.getSecond())));
  // The folowing code works:
  // TimeStamp = String(rtc.getYear()) + "-" + String(rtc.getMonth())  + "-" + String(rtc.getDay())  + " " + String(rtc.getHour(true))  + ":" + String(rtc.getMinute()) + ":" + String(rtc.getSecond());
  //Serial.println(buffer);
  return TimeStamp;
}