sudo update-alternatives --config gcc
There are 2 choices for the alternative gcc (providing /usr/bin/gcc)
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/bin/gcc-4.7 60 auto mode
1 /usr/bin/gcc-4.6 40 manual mode
2 /usr/bin/gcc-4.7 60 manual mode
Press enter to keep the current choice[*], or type selection number: 0