cpp -v命令可以檢視標頭檔案包含路徑，記錄一下。
linux下執行結果：

Using built-in specs.
COLLECT_GCC=cpp
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --enable-checking=release --enable-languages=c,c++ --disable-multilib
Thread model: posix
gcc version 4.9.1 (GCC) 
COLLECT_GCC_OPTIONS='-E' '-v' '-mtune=generic' '-march=x86-64'
 /usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.9.1/cc1 -E -quiet -v - -mtune=generic -march=x86-64
ignoring nonexistent directory "/usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.9.1/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.9.1/include
 /usr/local/include
 /usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.9.1/include-fixed
 /usr/include
End of search list.
 

windows下執行結果

Using built-in specs.
COLLECT_GCC=cpp
Target: mingw32
Configured with: ../src/gcc-6.3.0/configure --build=x86_64-pc-linux-gnu --host=mingw32 --target=mingw32 --with-gmp=/mingw --with-mpfr --with-mpc=/mingw --with-isl=/mingw --prefix=/mingw --disable-win32-registry --with-arch=i586 --with-tune=generic --enable-languages=c,c++,objc,obj-c++,fortran,ada --with-pkgversion='MinGW.org GCC-6.3.0-1' --enable-static --enable-shared --enable-threads --with-dwarf2 --disable-sjlj-exceptions --enable-version-specific-runtime-libs --with-libiconv-prefix=/mingw --with-libintl-prefix=/mingw --enable-libstdcxx-debug --enable-libgomp --disable-libvtv --enable-nls
Thread model: win32
gcc version 6.3.0 (MinGW.org GCC-6.3.0-1)
COLLECT_GCC_OPTIONS='-E' '-v' '-mtune=generic' '-march=i586'
 c:/mingw/bin/../libexec/gcc/mingw32/6.3.0/cc1.exe -E -quiet -v -iprefix c:\mingw\bin\../lib/gcc/mingw32/6.3.0/ - -mtune=generic -march=i586
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/6.3.0/include"
ignoring duplicate directory "/mingw/lib/gcc/mingw32/6.3.0/../../../../include"
ignoring duplicate directory "c:/mingw/lib/gcc/../../include"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/6.3.0/include-fixed"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/6.3.0/../../../../mingw32/include"
ignoring duplicate directory "/mingw/include"
#include "..." search starts here:
#include <...> search starts here:
 c:\mingw\bin\../lib/gcc/mingw32/6.3.0/include
 c:\mingw\bin\../lib/gcc/mingw32/6.3.0/../../../../include
 c:\mingw\bin\../lib/gcc/mingw32/6.3.0/include-fixed
 c:\mingw\bin\../lib/gcc/mingw32/6.3.0/../../../../mingw32/include
End of search list.