Developer tools (such as GCC) are an optional installation on macOS. Fortunately, they're easy to acquire.
You start with Xcode, which is available for free through the Mac App Store. Simply search for Xcode and click on the Get button. Once you have Xcode installed, open a Terminal window and type the following:
$ xcode-select --install
This installs the Xcode command-line tools:
For additional information, visit http://osxdaily.com/2014/02/12/install-command-line-tools-mac-os-x/.