I'm still on Ubuntu 22.04 LTS but needed g++14. The sudo apt-get gcc-14 did not work for me, as it installed clang++14 for some reason (perhaps a misconfiguration on my part). What did work for me was following the instructions I found at https://www.dedicatedcore.com/blog/install-gcc-compiler-ubuntu/

The steps I took:

sudo apt install build-essential
sudo apt install libmpfr-dev libgmp3-dev libmpc-dev -y
wget https://ftp.gnu.org/gnu/gcc/gcc-14.1.0/gcc-14.1.0.tar.gz
tar -xf gcc-14.1.0.tar.gz
cd gcc-14.1.0
./configure -v --build=$(uname -m)-linux-gnu --host=$(uname -m)-linux-gnu --target=$(uname -m)-linux-gnu --prefix=/usr/local/gcc-14.1.0 --enable-checking=release --enable-languages=c,c++ --disable-multilib --program-suffix=-14.1.0
make
sudo make install

And if you would like to make it the default:

sudo update-alternatives --install /usr/bin/g++ g++ /usr/local/gcc-14.1.0/bin/g++-14.1.0 14
sudo update-alternatives --install /usr/bin/gcc gcc /usr/local/gcc-14.1.0/bin/gcc-14.1.0 14

After that, g++ showed I was running version 14.1.0. I was then able to compile my project that included some c++20/23 features that were not in the previous versions of g++ (chrono/format).

On which OS?

I saw somebody link to this old post today. The best way to install GCC in homebrew right now is just brew install gcc. If you have the XCode Command Line Tools (they are separate from XCode; you can install them with xcode-select --install) installed, a precompiled version will be installed (which is very fast).

If you want to install it as a local user

GNU GSRC provides an easy way to do so

Link: http://www.gnu.org/software/gsrc/

After configuration, simply specify the following commands:

cd gsrc
make -C pkg/gnu/gcc 
make -C pkg/gnu/gcc install

The second step could also be changed to speed up for an N-core system:

make -C pkg/gnu/gcc MAKE_ARGS_PARALLEL="-jN"

If you have the most recent Apple Command Line Tools (macOS 10.nn) for Xcode installed for your operating system version — which you get from developer.apple.com/download/more, then you need a package manager (e.g. homebrew) to install, and compile GCC and all of its dependencies. That compilation process will take at least an hour. After you initially install homebrew (brew):# In the bash shell (e.g. .bash_profile), gag Google Analytics in Homebrew.export HOMEBREW_NO_ANALYTICS=1brew updatebrew upgradebrew info gccbrew install gccbrew cleanup (this removes previous application/dependency revisions saving considerable space)The gcc application will be installed by default in /usr/local/bin.Personally, I use Apple's clang/clang++ compilation tools rather than deal with GNU gcc.

You cannot install gcc in virtualenv — gcc is not a Python package. And you don't need to — Python virtual environments are used to separately install Python packages so you don't need a separate gcc in a virtual env.

If you really need to install a separate, non-system gcc, you probably need bigger virtualization solution — a container or a virtual machine.

You'll have to completely purge what you have and perform a fresh install.

Much of this is done automatically when using the GUI. But when using the commandline you have to be specific to remove the leftover packages and other files manually.

First completely purge/remove what you currently have installed, which isn't working. Clean and update your repository cache and packages, then freshly install gcc.

$ sudo apt purge gcc
$ sudo apt-get autoremove
$ sudo apt update
$ sudo apt upgrade
$ sudo apt full-upgrade
$ sudo apt install gcc

Check for errors between commands. There shouldn't be errors. If they are, address the suggested remedy provided to fix the error. For instance, there might be an occasional warning or error such as:

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

To resolve that particular state, run:

$ sudo dpkg --configure -a

Then after fixing that part, proceed to the next step.

Each of the commands should give a clean state. You'll then have a fresh install from the repository.

yum install centos-release-scl-rh
yum install devtoolset-3-gcc devtoolset-3-gcc-c++
update-alternatives --install /usr/bin/gcc-4.9 gcc-4.9 /opt/rh/devtoolset-3/root/usr/bin/gcc 10
update-alternatives --install /usr/bin/g++-4.9 g++-4.9 /opt/rh/devtoolset-3/root/usr/bin/g++ 10

gcc-7 and gcc-8 will happily co-live together.

I would suggest to let gcc-7 be installed, for satisfying build-essential and perhaps other dependent packages, and configure gcc-8 to be your default gcc installation.

Use update-alternatives for having gcc redirected automatically to gcc-8:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 700 --slave /usr/bin/g++ g++ /usr/bin/g++-7
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 800 --slave /usr/bin/g++ g++ /usr/bin/g++-8

This will give you the convenience of gcc being at the latest version, and still you will be able to invoke gcc-7 or gcc-8 directly.

If you'll wish to change the default gcc version later on, run sudo update-alternatives --config gcc. It will bring a prompt similar to this, which lets you pick the version to be used:

There are 2 choices for the alternative gcc (providing /usr/bin/gcc).

  Selection    Path            Priority   Status
------------------------------------------------------------
* 0            /usr/bin/gcc-8   800       auto mode
  1            /usr/bin/gcc-7   700       manual mode
  2            /usr/bin/gcc-8   800       manual mode

Press <enter> to keep the current choice[*], or type selection number: 

The higher priority is the one that is picked automatically by update-alternatives.

I wanted to install gcc-6 alongside my existing installation of gcc-9 and this is how I did it. First off, sudo apt install gcc-6 didn't work because the package wasn't found so I had to add a new repository that contained gcc-6. To do this, I first found a repository that contains gcc-6 from Google and ended up at: https://packages.ubuntu.com/bionic/gcc-6

From there, I chose an architecture (amd64) which took me to a page with all the mirrors. I added the first mirror (mirrors.kernel.org/ubuntu) to /etc/apt/sources.list and did sudo apt update and then installed gcc-6 with sudo apt install gcc-6.

To switch between gcc versions, I used the following:

sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-6 6
sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-9 9

sudo update-alternatives --config g++