Okkkkkkk................
But I think all those are being happend for yr compiler. I think you are not using TURBO C++ compiler. I am using that and haven't faced any problems so far... .
The prototype for delay() is specified in the Header file named dos.h and after including the file how an error msg may appear!?.
If your compiler is unable to include the header file then an error msg should appear. Is there any error msg specifying such kinds of error?