Ubuntu下安装gcc-4.9 g++4.9

＃Ubuntu下安装gcc-4.9 g++4.9

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
sudo update-alternatives –install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 –slave /usr/bin/g++ g++ /usr/bin/g++-4.9
sudo update-alternatives –config gcc

参考：
1. http://askubuntu.com/questions/466651/how-do-i-use-the-latest-gcc-4-9-on-ubuntu-14-04