You also have to look at the contents of the revisions. C99 was a massive update for C, and C11 was tiny in comparison (and C17 was basically nothing at all).

You also have to look at the contents of the revisions. C99 was a massive update for C, and C11 was tiny in comparison (and C17 was basically nothing at all). Writing C89, without variable declaration in a for loop, and without // comments, etc, feels ancient. C99 on the other hand is what defines how C looks today. This is also why the attitude is: if they jump to c99, they may as well jump to c11 because they are basically the same.