Stack OverflowWhat is the largest program ever written?
[+8] [7] Andy Brice
[2009-12-15 00:16:06]
[ language-agnostic historical ]

In a fit of idle curiosity, I was wondering that the largest program ever written was. What did it do? What language was it written in? How successful was it? How buggy was it? How many man years did it take to create?

I realise that 'largest' and 'program' are both a bit ill-defined. For the sake of argument I am defining it as a single process containing the largest number of executable statements.

(10) Should be community wiki. - Daniel Sloof
(2) Probably Windows; started on 80's, still buggy and not finished - Rubens Farias
(9) Duke Nukem forever has an estimated 10 trillion lines of code. - Dan Lorenc
No idea, but I'm guessing it's some government software. - Michael Stum
[+9] [2009-12-15 00:29:22] JohnFx

Here are some of the major contenders based on Lines of code. It isn't the best metric, but should give you a relative idea of the size of these projects.

    Project                     SLOC
    ------------------          -----
    Lucent 5ESS Switch          100m  	
    Windows Vista              50m 	
    Red Hat Linux 7.1          30m	
    Windows XP                40m 		 
    Visual Studio              40m 	
    MS Office                  30m 	

Source: "World's Largest Software Project" [1]


(3) Also notable that Fedora 9 is estimated on the same page at >200m LoC, by the cunning mechanism of throwing every potentially-useful line of code it can find into one enormous barrel, and calling that the product. It might be interesting to attempt a definition of "program" which doesn't include any of these projects. For example, a definition corresponding more closely to that in the C and C++ standards. Then again, it might turn into an exercise in "pick your winner, then set the rules". - Steve Jessop
I don't think operating systems count as programs, but the numbers are interesting nonetheless. - Andy Brice
(5) What the hell is that switch doing that it needs double the loc of Vista. - mP.
What switches do is a mystery, even to themselves. - Inuyasha
@mP Only controlling the entire cellular data network of the United States, would be my guess. -- - SpikeX
[+4] [2009-12-15 00:32:28] bmargulies

The entire universe is believed by some [1] people and at least one famous person [2] to be a program running on some rather specialized hardware.


define "some" and provide a link, and you, sir, have my vote. - echo
(5) Mostly written in Perl, of course: - Peter
(3) @Peter:Obviously the author of xkcd is a youngster. Everybody who's been around long knows that the universe came into being from a contest over who could do the most with a single line of APL. - Jerry Coffin
The program is rather small, it just uses a huge amount of data. ;-) - starblue
I was sure that "at least one famous person" was going to be Douglas Adams. You do realize the entire Earth is part of a computer program run by a hyper-race of mice, right? - JohnFx
[+2] [2009-12-15 00:17:10] srini.venigalla

I heard is is called "Xanadu"

[+2] [2009-12-15 00:29:42] Tor Valamo

Early Windows Hello World [1] app?


[+1] [2009-12-15 00:25:46] Brian

Visual Studio Team System 2008 was I think about 55 million lines of code, and is possibly the largest piece of commercial software ever, by that metric (I think it's a little bigger than Windows Vista was, anyway). It's mostly C++, with a smattering of C# and some other languages, I think. I think it represents many thousands of man-years of effort.

Interesting. Is the VS2010 version smaller/only-in-beta-so-doesn't-count-yet/other? - Steve Jessop
I don't know if 2010 will be bigger or smaller. I'm just mentioning 2008 because I recall seeing some poster on some wall after it shipped that had a bunch of stats including LoC, and at some point I heard someone say it was bigger than Windows (but only by a little). - Brian
[+1] [2009-12-16 11:16:08] starblue

In 1978 the largest program allegedly [1] contained 1 million lines (aka 1 million punchcards).


[+1] [2011-06-14 07:31:55] hitesh

The cost of developing all the packages included in Debian 5.0 lenny (323 million lines of code), using the COCOMO model, has been estimated to be about US$ 8 billion.