Send command for RC Car

ok, i understand your point.

But with my last experiences i have a problem with number bigger than 9.

For exemple if i want make a diference between my buttons and the values from my joystick (not implemented yet) in serial comunication, how can i do this?

Send a letter + a number like "L0"-> for Left Off and "L1"-> for Left On for my buttons and send my joystick value in int type?

I try to send this but i only receive the last characther it why i try with hexadecimal numbers