This is my attempt to collate and explain the most common errors and warnings you get when compiling code for the Arduino and Arduino-like boards.
Expected primary expression before '.' token
This is usually because you used a class name instead of an instance of a class. One example would be if you created an instance of the LiquidCrystal class:
LiquidCrystal lcd(4, 5, 6, 7, 8, 9, 10);
And then used something like: