c-preprocessor

If a value is defined as #define M_40 40 Is the size the same as a short (2 bytes) or is it as a char (1 byte) or int (4 bytes)? Is the size dependent on whether you are 32-bit or 64-bit? #define has no size as it's not a type but a plain text substitution into your C++ code. #define is a preprocessing directive and it runs before your code even begins to be compiled . The size in C++ code after substitution is whatever the size is of what C++ expression or code you have there. For example if you suffix with L like 102L then it is seen a long, otherwise with no suffix, just an int. So 4 bytes

This question already has an answer here: Is a C++ preprocessor identical to a C preprocessor? 3 answers Are there any differences in behaviour between the C and C++ preprocessors? They are defined by different passages of standards text (section 6.10 of the C standard and section 16 of the C++ standard ). My motivation for asking this is that a proposal for making the single quote a digit separator that was recently accepted into C++14 extends the C++ preprocessor grammar to accomodate this change (specifically, it extends the definition of a pp-number ), and I'm wondering whether this

If you have a header file named ThisIsAHeaderFile.h, the following will still locate the file in Visual Studio: #include <ThisIsAheaderFile.h> Is there a way to enforce case sensitivity so that the #include will result in an error? You can't, because the Windows file system is itself case-insensitive. If you could get into a situation where you had both RICHIE.h and richie.h, it might make sense to control case sensitivity, but you can't. It is (used to be?) possible to create files with the same name but case differences on NTFS. Maybe someone with cygwin can verify this. MSDN Even then,

Is there a way to run the GCC preprocessor, but only for user-defined macros? I have a few one-liners and some #ifdef , etc. conditionals, and I want to see what my code looks like when just those are expanded. As it is, the includes get expanded, my fprintf(stderr) s turn into fprintf(((__getreeent())->_stderr) , etc. Call cpp directly, e.g. $ cat >foo.c <<EOF #define FOO #ifdef FOO foo is defined #else foo is not defined #endif EOF $ cpp foo.c # 1 "foo.c" # 1 "<built-in>" # 1 "<command-line>" # 1 "foo.c" foo is defined Of course, if you include any headers then those will be included in the