How does one install GCC on a Mac?

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=1

brew update

brew upgrade

brew info gcc

brew install gcc

brew 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.

Do you need GCC or just a C compiler environment

<http://osxdaily.com/2014/02/12/install-command-line-tools-mac-os-x>

These instructions will give you a C compiler environment.

However, if you explicitly need GCC, then after installing the command line tools via the above link, you can follow VikingOSX's suggestions.