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Is there an option that the GCC preprocessor could generate C source code and filter out irrelevant source code?
For example, a .c file has a #define switch to define for many different platforms. I'm only interested in one platform, and I want the C preprocessor to filter out unrelated code.
Does GCC support this?
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Yes. Pass gcc the -E option. This will output preprocessed source code.
You can invoke the preprocessor either with the cpp command, or via gcc -E . In GCC, the preprocessor is actually integrated with the compiler rather than a separate program, and both of these commands invoke GCC and tell it to stop after the preprocessing phase.
The C preprocessor implements the macro language used to transform C, C++, and Objective-C programs before they are compiled. It can also be useful on its own.
The C preprocessor is a macro processor that is used automatically by the C compiler to transform your program before actual compilation. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs.
Yes. Use the -E option:
gcc -E foo.c While the -E option will perform all pre-processing, it also produces some very 'raw' output that might not be what you want (depending on what you want).
If you need to debug a macro expansion that's not doing what you expect, E is a good way to go. If you simply want to filter out the 'inactive code', but leave the remaining code in more-or-less original form, you might want to look at the answers to the following Stack Overflow question:
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