[glaberge@rostam1 cpp_test]$ clang++ main.cpp -o hello_world
[glaberge@rostam1 cpp_test]$ ls
Cmake_test  hello_world  main.cpp
[glaberge@rostam1 cpp_test]$ export CPLUS_INCLUDE_PATH=/usr/include/
[glaberge@rostam1 cpp_test]$ clang++ main.cpp -o hello_world
In file included from main.cpp:1:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/iostream:39:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/ostream:38:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/ios:42:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/bits/ios_base.h:41:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/bits/locale_classes.h:40:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/string:52:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/bits/basic_string.h:5417:
In file included from /opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/ext/string_conversions.h:41:
/opt/rh/devtoolset-6/root/usr/lib/gcc/x86_64-redhat-linux/6.3.1/../../../../include/c++/6.3.1/cstdlib:75:15: fatal error: 'stdlib.h' file not found
#include_next <stdlib.h>
              ^~~~~~~~~~
1 error generated.
[glaberge@rostam1 cpp_test]$ why?????