printf("%c", 0);
	could produce unexpected results

the utf function was in the wrong place, so never worked.

another issue, although less trivial, and probably not
a bug, is that, i'd expect this:
	awk 'BEGIN {s="arble z a b c d"; split(s, a, " "); for(i in a){printf("''%s''\n", i)}}'
to print:
'z'
'a'
'b'
'c'
'd'
[or some permutation of the above]

but it doesn't; it actually prints:
'2'
'3'
'4'
'5'
'6'
'1'

this is probably just awk being its usual nasty, unintuitive self.