How to install gcc-4.8 and g++-4.8 on Ubuntu 12.04

install_gcc_g++_4.8_ubuntu_12.04.txt

# link: http://askubuntu.com/questions/271388/how-to-install-gcc-4-8?newreg=6c2b1c109685438c8bc7b37a87cefb21
# link to the repository: https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test?field.series_filter=precise

# Open a terminal(Ctrl+Alt+t) and run the following commands:
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update

# install gcc
sudo apt-get install gcc-4.8
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50

# install g++
sudo apt-get install g++-4.8
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 50

# check gcc and g++ version
gcc --version