A frequently asked question on Mac programming forums is "Can I write C++ programs on Mac OS X?". Yes, you can write C++ programs on Mac OS X
Install the Xcode Tools
The Xcode Tools contain everything you need to write Mac OS X applications, including C++ programs. Every copy of Mac OS X contains the Xcode Tools. If you have Mac OS X 10.4, there should be an item called Xcode Tools on the Mac OS X DVD. This item contains the installer. Older versions of Mac OS X that ship on multiple CDs contain either an Xcode Tools or Developer Tools CD.
Apple frequently updates the Xcode Tools so the version that shipped with your copy of Mac OS X is most likely not the most recent version. If you have a broadband Internet connection, I recommend going to Apple's developer page and signing up for a free ADC membership. After signing up for an ADC membership, you can download the most recent version of the Xcode Tools.
One common concern people have when installing the Xcode Tools is the size of the install. The easy install of the Xcode Tools is over 1.5 GB, which is overkill if all you want to do is learn C++. You can perform a custom install of the Xcode Tools to reduce the size of the install. If you are low on disk space, the easiest way to save space is to not install the developer documentation. The developer documentation takes about 1 GB of disk space, and you can view all the documentation online anyway.
Writing Standard C++ Programs
The people most likely to ask if they can write C++ programs on Mac OS X are Mac-using college students who are taking a class on C++ programming. C++ programming classes normally teach standard C++, which will run on most operating systems, including Mac OS X.
To write a standard C++ program with Xcode, you must create a C++ Tool project. C++ Tool projects are used to write command-line programs without a GUI, which makes programming easier. You can read an article on the Xcode Tools Sensei page that contains detailed instructions on creating and building a C++ Tool project.
Writing C++ GUI Programs
After learning C++ you may want to use your newfound knowledge to write Mac OS X GUI programs. You have three options for writing Mac GUI applications in C++. First, you can use Cocoa, writing your user interface code in Objective C and the rest of your code in C++. You must give your Objective C files the extension .mm, which tells Xcode to treat them as Objective C++ files. Objective C++ lets you mix C++ and Objective C code in the same source file.
Second, you can use Carbon, which is Apple's C API for writing GUI applications. If you choose to use Carbon, you may want to look into Nano, an open-source C++ framework built on top of Carbon.
Third, you can use a C++ cross-platform GUI framework like Qt or wxWidgets. I haven't used either of these frameworks, but you should check them out if you are interested in supporting Linux and Windows as well as Mac OS X.