struct _data {
  char key[8];
  char val[16];
}
Data = {
  "type","2"
};


String makeDateStr(const int (&arr)[3]) {
  String val = "";
  int index = 0;

  for (const int &n : arr) 
    val = val
    + ((n<10)?"0":"") 
    + String(n) 
    + ((++index < 3) ? "-" : "");

  return val;
}

String makeTimeStr(const int (&arr)[3]) {
  String val = "";
  int index = 0;

  for (const int &n : arr) 
    val = val
    + ((n<10)?"0":"") 
    + String(n) 
    + ((++index < 3) ? ":" : "");

  return val;
}

void setup() {
  Serial.begin(9600);
  const char* num;
  num = Data.val;
  int x = atoi(num);
  Serial.println(x+1);

  int y = 2025;
  int m = 8;
  int d = 18;
  int H = 13;
  int M = 45;
  int S = 52;

  String dateStr = makeDateStr({y,m,d});
  Serial.print("date: "); Serial.println(dateStr);

  String timeStr = makeTimeStr({H,M,S});
  Serial.print("time: "); Serial.println(timeStr);

}

void loop() {
  // put your main code here, to run repeatedly:

}