Why are most of the biggest open source projects in C? [closed]

Question

I'm having a debate with a friend and we're wondering why so many open source projects have decided to go with C instead of C++. Projects such as Apache, GTK, Gnome and more opted for C, but why not C++ since it's almost the same?

We're precisely looking for the reasons that would have led those projects (not only those I've listed but all C projects) to go with C instead of C++. Topics can be performance, ease of programming, debugging, testing, conception, etc.

Answer 1

C is very portable, much more than C++ was 10 years ago.

Also, C is very entrenched in the Unix tradition. Read more in 'The Art of Unix Programming', about Unix and OO in general, and about specific languages on unix (including C and C++).

Answer 2

There are numerous counter examples: everything based on Qt for one.

Also, on my Debian testing system:

edd@ron:~$ apt-cache rdepends libstdc++6|wc -l
4101

So that's 4101 packages depending on the basic C++ library. For comparison, I get about 14,982 for libc6 or roughly 3.6 as many. But it is not if there aren't any C++ projects in Open Source land.

Edit: Thinko on my part: as the C++ packages also depend on libc6, the ratio really is

(14982 - 4101)/4101 = 2.65

so there are roughly 2 1/2 times as many packages implemented in C than there are in C++.

Answer 3

Eric Raymond's wonderful book "The Art of Unix Programming" has some reflections on this issue (the whole book is well worth reading in either the paper or free online editions, I'm just pointing to the relevant section -- Eric was involved with the coining and introduction of the term "open source", and is always well worth reading;-0).

Summarizing that section, Raymond claims that "OO languages show some tendency to suck programmers into the trap of excessive layering" and Unix programmers (and by extension open-source programmers) resist that trap of "thick glue".

Later in the book, you find some considerations specifically about C++, such as "It may be that C++'s realization of OO is particularly problem-prone". Whether you agree or not, the whole text is well worth reading (I can hardly do it justice here!-), and rich with bibliography pointing you to many other relevant studies and publications.