Can't access a #defined constant in C

Question

This is a C program that I was using, in the header file I define an offset:

#define LDR_DATA_PATHFILENAME_OFFSET    0x24    // MODULE_ITEM.PathFileName

Later in the program I use it as following:

pImageName = (PUNICODE_STRING)( ((DWORD)(pUserModuleListPtr)) + 
(LDR_DATA_PATHFILENAME_OFFSET-dwOffset));

When inspecting the value of LDR i get an CXX0017: Error: symbol "LDR_DATA_PATHFILENAME_OFFSET" not found. Erm, its defined, it compiles, but yet it can't access the value! What am I doing wrong?

Answer 1

I am assuming that you are debugging your application because you said "inspecting": Symbolic constants are substituted by its values at compile time. At runtime you can´t see them anymore.

Answer 2

Find the option in your compiler to dump preprocessed source so you can see what's really going on. Your symbol may have gotten undefined, or your header isn't included correctly as you expect.

Answer 3

Are you using an older C compiler? You're using a C++ style comment // instead of the C style comment of /* */. Older C compilers won't recognize the //.

Answer 4

Are you sure your header file is being included? Easy check - copypaste the #define from the header file to the beginning of your C file.

Double check the #ifndef guards in your header file.