Centos7 and Redhat7 still uses too old gcc 4.8.5 version and this becomes very annoying if you want to use newer features in your C/C++ programs.
You can install these newer versions with Devtoolset-4 from the Software Collections project.
First of all enable software collections repo:
sudo yum install centos-release-scl
Now you can install gcc-6.x, gcc-7.x etc. with proper parameter like below:
sudo yum install devtoolset-6-gcc*
This method brings newer versions without uninstalling or overwriting existing ones. For this reason, you have to enable devtoolset in current shell before using gcc:
scl enable devtoolset-6 bash
And check the gcc version:
$ gcc -v
gcc version 6.3.1 20170216 (Red Hat 6.3.1-3) (GCC)