Using dynamic addresses with functions Firebase.RTDB.set(&obj,F(dir.),value);, error: nitializer fails to determine size of '__pstr__'

[vicgig90]

Hi everyone!
I'm trying to send data to a FB RTDB using the function Firebase.RTDB.setString(&obj, F(dir. string),value); with an ESP8266. However the compiler keeps sending the next messages:

• error: initializer fails to determine size of ' pstr '
• error: array must be initialized with a brace-enclosed initializer

I have fixed them by writing a string as the argument for the direction of the RTDB (dir.string), however I need to send data to different directions, for instance:

• /root/data/dir1, /root/data/dir2, /root/data/dir3, /root/data/dir4, etc.

So, I need to use changing strings as addresses. Regularly I do this by:
for(int counter=0; counter <=anyvalue; counter ++){
Firebase.RTDB.setString(&obj, F("dir"+String(counter)),value)
}
But when I do that, the aforementioned errors occur. I guess that's because the compiler can't determine how big the String for the address is at compile time. So...
Has anyone had the same trouble?
If so,
have you been able to fix it? How?
Thanks in advance.

[mobizt]

The F macro cannot be used like that, and it is not necessary to use it.
F("dir"+String(counter))

You should write something like this instead.
"dir"+String(counter)

[vicgig90]

Thanks so much mobizt. It worked like a charm! Also thanks for answering that fast.