运行＆QUOT;光＆QUOT; preprocessor为GCC [英] Run a "light" preprocessor for GCC

问题描述

有没有一种方法来运行 GCC preprocessor，但仅限于用户可定义的宏？

Is there a way to run the GCC preprocessor, but only for user-defined macros?

我有几个单行有的 #IFDEF 等条件语句，我想看看我的code相时，只是那些被扩展样。

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.

由于它是，包括得到扩展，我的 fprintf中（标准错误）转成 取值fprintf中（（（__ getreeent（）） - GT; _stderr）等

As it is, the includes get expanded, my fprintf(stderr)s turn into fprintf(((__getreeent())->_stderr), etc.

推荐答案

呼叫 CPP 直接，例如。

$ 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

当然，如果包括头那么这些将被包含在输出中。为了避免可能的一种方式，只是的grep -v 出与的#include 行S（或者只是那些与的#include＆LT; ，并允许的#include）或者，您可以指定 - nostdinc 选项删除只是标准的包括（但在当地的图书馆可能离开，除非您指定包含路径，使它们不会被发现） - 这会警告缺少头，虽然

Of course, if you include any headers then those will be included in the output. One way to avoid that might be to just grep -v out the lines with #includes (or perhaps just ones with #include < and allow #include "). Or you could specify the -nostdinc option to remove just standard includes (but possibly leave in local libraries unless you specify include paths so that they won't be found) - this would warn about missing headers, though.

编辑：或者使用preprocessor本身，使头有条件的纳​​入，将它们包装在类似的#ifndef TESTING_ prePROCESSOR ，并使用 -DTESTING_ prePROCESSOR 。

Or use the preprocessor itself to make the inclusion of headers conditional, wrap them in something like #ifndef TESTING_PREPROCESSOR and use -DTESTING_PREPROCESSOR.

这篇关于运行＆QUOT;光＆QUOT; preprocessor为GCC的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！