Building C++ not working in OSX 10.9

[Added 2019 - Mojave/Catalina] XCode 10 has removed the placement of headers in /usr/include, even with the command line tools. If you want headers, and you're on you should be able to install a transitional package, which is available on Mojave. This package is not present on the Catalina. The headers are within the SDK for the appropriate release.

XCode 5/Mavericks have changed the defaults for where headers are located.

On prior versions of Mac OS X / XCode you would have found headers in /usr/include.

When you built gcc on the older release it picked up the headers from that location, and looks for them there now when you try to build code.

The problem is that the files are not there; they're somewhere under /Applications/Xcode.app/Contents/Developer.

You could futz about with a spec file to get it working consistently again, but the sanest thing to do is rebuild gcc.

As has been mentioned as well, you can install the command line tools using xcode-select --install, which will reinstall the developer tools, including the headers in /usr/include.

I tend to reinstall things like gcc when I upgrade my operating system as I encounter other errors due to changes in the environment. This is just a habit I've formed. It may not be the best habit, but it's saved me pain on numerous occasions.

[added 2017] As an addendum, if you install the command line tools, then the headers will be placed in /usr/include as well. The command to install the command line tools is xcode-select --install - this will allow you to use most compilers without having to specify the location of the headers manually.

This is how I got it working on Mac osx Mavericks:

1. Open terminal

2. type --> xcode-select --install

3. A pop-up windows will apear asking you about install tools

4. choose install tools

5. wait install to finish