I am getting this error: error C202 'P3_3' undefined identifier.. please tell me what changes to make in my program. I am using 89c51
Just remember that the OP seems to have copied som random code. The code will not work if the correct hardware isn't connected to the relevant pins - assuming the code did work originally.
And while the OP doesn't seem to understand the code, the code is written by someone who names the pins based on pin location instead of function. So lots of confusion is likely.