My paper copy of K&amp;R1 (1978) does not mention void, nor does it mention standard headers other than stdio.h. The linked document may be a later draft (and it&#x27;s almost certainly a copyright violation).<p>Prior to C99, reaching the closing &quot;}&quot; of main() caused the program to return an undefined status to the calling environment. In C99 and later (as in C++), reaching the closing &quot;}&quot; does an implicit &quot;return 0;&quot;.