how to use the c51 compiler for example if i use c51 -C main.c it is giving error like c51 FATAL-ERROR - ACTION: PARSING INVOKE-/#PRAGMA - LINE LINE: C:\KEIL\C51\BIN\c51.exe -C main.c ERROR: UNKNOWN CONTROL C51 TERMINATED.
What ever made you think '-C' was an option recognized by the C51 compiler? It's not. To find out what the actual options are, consult the Manual --- that's what you have it for.