我将gcc，g ++的版本从7.3.0降级到4.8.5
$ gcc -v
gcc version 4.8.5 (Ubuntu 4.8.5-4ubuntu8)
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../:/lib/:/usr/lib/
但是，编译器使用7.3.0库。
// globals.h
11: #include <ostream>
// error
In file included from .././src/globals.h:11:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/ostream:38:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/ios:42:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/ios_base.h:41:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/locale_classes.h:40:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/string:52:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/basic_string.h:6352:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/ext/string_conversions.h:41:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/cstdlib:77:
/usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/std_abs.h:102:3: error: support for type '__float128' is not yet
implemented
abs(__float128 __x)
如何更改默认库路径？