John Carmack's Comments On C/C++
Written by Michael Larabel in Gaming on 14 January 2013 at 02:44 PM EST. 66 Comments
John Carmack, the veteran game programmer that co-founded id Software and was the lead developer on the id Tech engine and their most popular game titles, has shared some new opinions on C/C++ programming as it pertains to the id Tech game engine.

As a comment to an article about The exceptional beauty of Doom 3's source-code, Carmack responded himself with some additional food for thought about C++ and C.
In some ways, I still think the Quake 3 code is cleaner, as a final evolution of my C style, rather than the first iteration of my C++ style, but it may be more of a factor of the smaller total line count, or the fact that I haven’t really looked at it in a decade. I do think "good C++" is better than "good C" from a readability standpoint, all other things being equal.

I sort of meandered into C++ with Doom 3 – I was an experienced C programmer with OOP background from NeXT’s Objective-C, so I just started writing C++ without any proper study of usage and idiom. In retrospect, I very much wish I had read Effective C++ and some other material. A couple of the other programmers had prior C++ experience, but they mostly followed the stylistic choices I set.

I mistrusted templates for many years, and still use them with restraint, but I eventually decided I liked strong typing more than I disliked weird code in headers. The debate on STL is still ongoing here at Id, and gets a little spirited. Back when Doom 3 was started, using STL was almost certainly not a good call, but reasonable arguments can be made for it today, even in games.

I am a full const nazi nowadays, and I chide any programmer that doesn’t const every variable and parameter that can be.

The major evolution that is still going on for me is towards a more functional programming style, which involves unlearning a lot of old habits, and backing away from some OOP directions.

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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter or contacted via

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