I use the following statement in my include file to define a new data type: #define DWORD unsigned long however, the compiler give me the following warning: Warnning C317:redefinition of macro 'DWORD'. but i never defined it anywhere in my source files! pls give me some help!
Read the section, "Absolute Memory Access Macros" in the C51 manual! BTW: Why are you using #define rather than typedef? BTW2: I presume you're doing this to get a compiler-independent 32-bit type? However, the name "DWORD" is ambiguous in this application; I would prefer to use a name like "U32" (meaning, "Unsigned 32-bit). Just my opinion.
1) cannot use typedef; 2) after i change DWORD into UWORD, the warnning disappers! thanks, Lu Yunfeng
1) cannot use typedef; Why not? 2) after i change DWORD into UWORD, the warnning disappers! Of course it does - you are no longer in conflict with Keil's DWORD I still recommend that you should avoid "WORD" as it is ambiguous; U32 tells you unambiguously (and fairly intuitively) that it's Unsigned and 32 bits. And it's shorter to type into the bargain! ;-)