How can I get a list of all preprecoesor directives and their values ? specifically #define

I don't think that would be sensible, or if you had such a tool, that it would give you results that you'd consider sensible. That tool would have to scan the code, the include files included by that code, the include files included by the include files, and so on, down to the most rmeote system header file that is somehow in some obscure way connected. Even the most trivial program therefore would end up listing thousands of symbols defined in system headers that you've never heard of and that you're definitely not interested in.

What's more, most of these symbols would only be defined in a limited scope of the headers and code files. So, even if you somehow manage to spot a symbol you're interested in, you woldn't know which part of the code is aware of it, and which isn't.

In the end, you'd still need Albert's code to find out whether that symbol is actually known at the specific location in your code that you're interested in.

What you need very much depends on what you want to do with that information.

If you want to make sure that a new symbol name you're thinking of doesn't collide with an already existing one, my advice is (a) not to use #define at all, unless you absolutely cannot avoid it and (b) simply go by the general guidelines for choosing #define symbols.

Otherwise, Alberts solution seems fine to me.

Hi, Naming clashing is by no means what I am interested in. All the code I work on is contained in namespaces, so this is not an issue I am bothered about. I think you missed the point of what I am asking, what I want is a way to tell what pre-processor defined code will be included in the current build config.
The results would be totally sensible, and exactly what I want. I do want to know every pre-processor variable's state, in order to ascertain what the compiler will build. The code in this solution is written this way due to it being a huge project with 400 projects in various languages, assembler, C, C++, C#, and scripts etc. It has to compile on 9 different platforms, and can be both native and cross compiled, so it relies heavily on code gen and platform specific code that is controlled by the pre-processor. I am asking if there is a tool that exists that would grep for all the #define, then create a fiel to dump them in using the generic macro of #ifdef <pre-proc directive> #pragma message("VAR" state is blah #else #prgma message <pre-proc dir> NOT defined #endif. I'm sure other people when they see a line of code like this #if (define MONKEY) && !(define DOG) || RELEASE || (DEBUG && FOG) || NO_TRACE && GOAT etc.

Well, #define symbols completely ignore namespaces, so those will not protect you from nameclashes. Point in case: some windows header file(s?) #define the macros min and max, which clash with e. g. std::valarray::min() and std::valarray::max() (not sure if this is still the case with VS2015)

As for grepping all #defines, I already pointed out above how that would get you thousands of symbols defined in system headers in addition to those defined in your projects. I have some serious doubt that you will find that useful.

However, if your goal is to find out what code is actually included in your build, then just send your code through the preprocessor without compilation. In VS this should be possible using the /P switch - see http://stackoverflow.com/questions/277258/how-do-i-see-a-c-c-source-file-after-preprocessing-in-visual-studio for more information.