I installed g++ using those commands line:
sudo add-apt-repository ppa:jonathonf/gcc-7.1
sudo apt-get update
Then
sudo apt-get install gcc-7 g++-7
When it was done I tried g++ -v but still shows me the old version
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)
Am I not upgrading it correctly?
Edit
:~$ dpkg -L g++-7
/.
/usr
/usr/lib
/usr/lib/gcc
/usr/lib/gcc/x86_64-linux-gnu
/usr/lib/gcc/x86_64-linux-gnu/7
/usr/lib/gcc/x86_64-linux-gnu/7/cc1plus
/usr/share
/usr/share/doc
/usr/share/doc/gcc-7-base
/usr/share/doc/gcc-7-base/C++
/usr/share/doc/gcc-7-base/C++/README.C++
/usr/share/doc/gcc-7-base/C++/changelog.gz
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/x86_64-linux-gnu-g++-7.1.gz
/usr/bin
/usr/bin/x86_64-linux-gnu-g++-7
/usr/share/doc/g++-7
/usr/share/man/man1/g++-7.1.gz
/usr/bin/g++-7
:~$ which g++
/usr/bin/g++