How to switch your gcc/g++ version in ubuntu

Generally, we need to keep multiple versions of gcc/g++ to fit our compiling environment. This blog can teach you how to switch your system gcc/g++ version in ubuntu system.

Step 1: Check your current gcc/g++

gcc -v

get info like
gcc version 4.4.6 (Ubuntu/Linaro 4.4.6-llubuntu2)

Step 2: How about switching to gcc 4.5? Check if you already installed the gcc 4.5

ls /usr/bin/gcc*

If you can see /usr/bin/gcc-4.5, see step 4.

Step 3: Install gcc 4.5 and g++ 4.5

sudo apt-get install gcc-4.5 gcc-4.5-multilib g++-4.5 g++-4.5-multilib

then

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.4 50
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.4 50
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.5 40
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.5 40

Step 4: Config your gcc/g++ version

config gcc:

sudo update-alternatives --config gcc

get info like:

Selection    path               Priority    Status
--------------------------------------------------------------------
* 0          /usr/bin/gcc-4.4   50          auto mode
  1          /usr/bin/gcc-4.4   50          manual mode
  2          /usr/bin/gcc-4.5   40          manual mode
  3          /usr/bin/gcc-4.6   30          manual mode

Press ENTER to maintain, or type the selection number to the corresponding version.

then config g++ similarly:

sudo update-alternatives --config g++

NOTE

if you want to delete a version,

sudo update-alternatives --remove gcc /usr/bin/gcc-4.5