I have g++ 4.6, 4.7 and 4.8 installed, but not g++ itself. I am using Ubuntu 12.04. If I do:

g++ --version

it says:

The program 'g++' can be found in the following packages:
 * g++
 * pentium-builder

I have tried the following:

sudo apt-get update

then

sudo apt-get -f install

then

sudo apt-get install g++

but still I get the same when checking g++ version. Please help?

Doing apt-cache policy g++ yields:

g++:
  Installed: 4:4.6.3-1ubuntu5
  Candidate: 4:4.6.3-1ubuntu5
  Version table:
 *** 4:4.6.3-1ubuntu5 0
        500 http://gb.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status