Getting string from serial

Hello,
I want to read an uart sensor that returns a string (RFID tag id). I want to use a software serial port to read the sensor. My question is how do I read whole strings from serial?

You don’t.

You read serial data, and put that in an array.
Nick Gammon (the master Yoda of the Arduino universe) has a few examples (click) you can try.

And I wouldn't be me if I didn't (yet again) point out my little tutorial and example code: http://hacking.majenko.co.uk/reading-serial-on-the-arduino

Hi majenko.
I wasn’t aware of that one yet, i’ll check it out tomorrow.

My question is how do I read whole strings from serial?

Serial bytes are usually read one at a time from the serial source and formed into a c-string or String for use.

I have an RFID reader sketch here: