Hi,

You wrote:
i have seen the tutorial. but the clear function in the tutorial need to write a few line, but i have seen that some program just include the function in the program. how do it function

The program that you saw, just including the function clear in the program, has that function declared somewhere in the program (either as a call routine or included file). If this is not your case then definitely the answer to your question is in specific instructions set of your controller display. Could you tell us what type of controller/display did you use ?

Regards,
Silviu