arduino: loop until int gets value assigned to it

Question

I am trying to get a value from serial input. The rest of the programm behaves different if the value changes. This value gest assigned once in the ```void setup()``` function.
My goal is to let the program run an infinite loop or something similar until a value (type int) is recived, and only then resume the flow.
I know about ```Serial.parseInt()``` and tried to implement it ``` while (variable == null) variable = Serial.parseInt() ``` but I got an error that 'null' was not declared in this scope.
Any suggestions?

Answer 1

Oke, i was kinda dumb. There is an easy way, simply check

while (!variable) 
  variable = Serial.parseInt()

This worked for me and should work for you as well