1. sudo add-apt-repository ppa:ubuntu-toolchain-r/test

2. sudo apt-get update

3. sudo apt-get install gcc-7

4. sudo apt-get install g++-7

出现以下错误：

Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:gcc-7 : Depends: cpp-7 (= 7.5.0-3ubuntu1~16.04) but it is not going to be installedDepends: libgcc-7-dev (= 7.5.0-3ubuntu1~16.04) but it is not going to be installedwine-wechat : Depends: wine-stable but it is not installable
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

sudo apt --fix-broken install
 

然后继续：

sudo apt-get install gcc-7

切换gcc版本

1. sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 100

2. sudo update-alternatives --config gcc

gcc

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 100
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-5 100

g++
 

sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-7 100
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-5 100
 

参考：

https://blog.csdn.net/HelloJinYe/article/details/107404031

https://blog.csdn.net/weixin_35762621/article/details/80336291?utm_medium=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param#commentBox