xcode - On mac, g++ (clang) fails to search /usr/local/include and /usr/local/lib by default

Question

I'm on a mac and I used homebrew to install gmp.

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx
In file included from main.cpp:2:
./gcjlib.hpp:4:10: fatal error: 'gmpxx.h' file not found
#include <gmpxx.h>
         ^
1 error generated.

So then I explicitly told g++ to use /usr/local/include

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx -I/usr/local/include
ld: library not found for -lgmp
clang: error: linker command failed with exit code 1 (use -v to see invocation)

So then I explicitly told g++ to use /usr/local/lib

Kyumins-iMac:gcjlib math4tots$ g++ main.cpp -lgmp -lgmpxx -I/usr/local/include -L/usr/local/lib
Kyumins-iMac:gcjlib math4tots$ ./a.out 
sum is -4444
absolute value is 4444

So the only issue seems to be that g++ fails to acknowledge /usr/local.

But it is tedious to type all this out all the time, especially when I'm just writing small single file programs.

Is there a way for me to get g++ to acknowledge the stuff in /usr/local by default? Is there a standard way homebrew users do this?

---

I'm on OS X 10.9.3 with Xcode 5.1.1 in case it is relevant.

question from:https://stackoverflow.com/questions/23905661/on-mac-g-clang-fails-to-search-usr-local-include-and-usr-local-lib-by-def

Answer 1

I also use Homebrew and had a similar problem on Mac OSX Maverick 10.9.5 and Xcode 6.0.1, but it was solved by running:

xcode-select --install

Note that it doesn't work without the double hyphens given by the previous answer. This installs the command-line tools that also create /usr/lib/ and /usr/include/. I don't know why Homebrew doesn't automatically check this upon installation, since it does check for Xcode...

If you want to check exactly what folders your compiler is looking through for header files you can write:

cpp -v