also, why does everyone but me just assume in their solution that user will be well-behaved
and only enter a single letter? i know we're not writing production code here, but it seems a
little odd to me that i was the only one to bother to do 'substr $input, 0, 1'.
Perhaps it is a bleed-over of Perl's DWIM concept.
It seems logical (to me, at least)
that if the user inputs a string rather
than a single character the program should return
all lines beginning with that string. But then I imagine
it is just as logical to you that the program should
only use the first character as the search prefix.
In legitimate production code
where we are concerned about how many characters
the user inputs, it would probably be better to allow
only one character--rather than an entire line--to be
input in the first place (don't want to confuse those
end-users). And since the OP does say 'letter',
we'd also reject any input that isn't one.
