Comment by sfpotter

C's support for modularity is actually rather strong. This PDF gives a good overview of the basic techniques available: http://www.metamodulaire.org/Computing/modular-c.pdf

It may not be immediately obvious how to approach modularity since it isn't directly accomplished by explicit language features. But, once you know what you're doing, it's possible to write very large programs with good encapsulation, that span many files, and which nevertheless compile quite rapidly (more or less instantaneously for an incremental build).

I'm not saying other languages don't have better modularity, but to say that C's is bad misses the mark.