It's what historic Unix did: https://github.com/v7unix/v7unix/blob/master/v7/usr/src/libc/stdio/puts.c https://github.com/v7unix/v7unix/blob/master/v7/usr/src/l

It's what historic Unix did: https://github.com/v7unix/v7unix/blob/master/v7/usr/src/libc/stdio/puts.c https://github.com/v7unix/v7unix/blob/master/v7/usr/src/libc... Why it did that? I'm not sure, but at the time C did not have 'void' functions: every function returned a value. They probably wanted to make the behavior of the stdlib functions deterministic, even if the return value was useless and undocumented.