ubuntu failed to install GCC G++ solution

Via sudo apt-get install gcc g++.

The following error occurred when installing GCC G++:

 

1. Use the following command to modify the source Open the source.list file

sudo gedit /etc/apt/sources.list

2. Add the following source to the opened file (add these two lines at the end)

1. deb http://dk.archive.ubuntu.com/ubuntu/ xenial main

2. deb http://dk.archive.ubuntu.com/ubuntu/ xenial universe

Perform the third step after saving.

3. Use the following command to update the source

sudo apt update

If  E: Unable to obtain lock /var/lib/apt/lists/lock-open (11: The resource is temporarily unavailable) E: Unable to lock the directory /var/lib/apt/lists/ 

Then enter the command in the terminal

sudo rm /var/lib/apt/lists/lock

The terminal display will be as shown below. 

This process may take a while

If it still does not work, please execute the following command to resolve the dependency

sudo apt-get install ncurses-dev
sudo apt-get install bison
sudo apt-get install flex
sudo apt-get install build-essential

4. Use commands to install g++4.9, gcc4.9

sudo apt install g++-4.9
sudo apt install gcc-4.9