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
Isn't it obvious what to do when the code tries to reference an unknown symbol?
But you must figure out if you have spelled wrong or not written all required statements yet. Should be easy since you are expected to know the meaning of P3_3 (third bit on port P3???) If you don't, then your code is a partial cut/paste of code you don't understand, in which case you have bigger problems than just supplying all required definitions/declarations.
the default symbol is P3^3 need something like that sbit P3_3=P3^3;
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.