Listing all the #defines in a C program

Question

hi,

Is it possible to get the list of #defines(both compile time and defined in the source code) used in a C program while execution. Because i am having a project having lot of C source files.

Is there any compile time option to get that?

__Kanu

Answer 1

GNU cpp takes various -d options to output macro and define data. See their man pages for more details.

Answer 2

for gcc, you can use one of the following:

-dCHARS CHARS is a sequence of one or more of the following characters, and must not be preceded by a space. Other characters are interpreted by the compiler proper, or reserved for future versions of GCC, and so are silently ignored. If you specify characters whose behavior conflicts, the result is undefined.

M' Instead of the normal output, generate a list of#define' directives for all the macros defined during the execution of the preprocessor, including predefined macros. This gives you a way of finding out what is predefined in your version of the preprocessor. Assuming you have no file foo.h, the command touch foo.h; cpp -dM foo.h

will show all the predefined macros.

If you use -dM without the -E option, -dM is interpreted as a synonym for -fdump-rtl-mach. See Debugging Options.

D' LikeM' except in two respects: it does not include the predefined macros, and it outputs both the #define' directives and the result of preprocessing. Both kinds of output go to the standard output file. N' Like `D', but emit only the macro names, not their expansions.

I' Output#include' directives in addition to the result of preprocessing.

U' LikeD' except that only macros that are expanded, or whose definedness is tested in preprocessor directives, are output; the output is delayed until the use or test of the macro; and `#undef' directives are also output for macros tested but undefined at the time.