How to Remove Comments from C/C Code Without a Preprocessor?

How to Strip Comments from C/C Source Code

Removing comments from a C/C source file without using a preprocessor can be a useful task for various reasons. Fortunately, there is an existing tool that can efficiently handle this task: the GNU Compiler Collection (GCC).

Using GCC to Strip Comments

To remove comments from a source file using GCC, execute the following command:

gcc -fpreprocessed -dD -E -P test.c

Explanation of GCC Flags:

• -fpreprocessed: Generates and prints the preprocessed output without compiling the code.
• -dD: Undefines all macros.
• -E: Preprocesses the code only, without compiling or assembling.
• -P: Suppresses line numbers and macro expansion directives in the output.

Example Usage:

Consider the following sample source code file test.c:

#define foo bar
foo foo foo
#ifdef foo
#undef foo
#define foo baz
#endif
foo foo
/* comments? comments. */
// c++ style comments

Executing the above GCC command on test.c will produce the following output:

#define foo bar
foo foo foo
#ifdef foo
#undef foo
#define foo baz
#endif
foo foo

As you can see, all comments have been successfully removed, while the rest of the code remains unchanged. This method provides a reliable and automated approach to strip comments from C/C source code without the need for custom regex implementations or manual editing.

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