read from keyboard non blocking

hey there

is there a way to read from keyboard without breaking a program in C.

meaning if I use getchar the prog waits for new input from the keyboard but I want the program to be executed until it gets a stop character. I know I can use multi threading but is there s tutorial on something simpler?

OP:

my program is not read file or anything else, I get some data from a micro controller and feed it back some acsii characters, I want the program to run all the time until stop key is pressed.

Everything else is done I just need to see how to make the loop non blocking until event