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can someone please help me understand what's going on here
lists:dropwhile(fun(X) -> X < 8 end, lists:seq(1,10)).
"\b\t\n" % ??? what is this ? why not [8,9,10]
lists:dropwhile(fun(X) -> X < 7 end, lists:seq(1,10)).
[7,8,9,10] % this is correct
314
You can use length() to find the length of a list, and can use list comprehensions to filter your list. num(L) -> length([X || X <- L, X < 1]).
you will create a new list which is copy of the elements in List1, followed by List2. Looking at how lists:append/1 or ++ would be implemented in plain Erlang, it can be seen clearly that the first list is copied: append([H|T], Tail) -> [H|append(T, Tail)]; append([], Tail) -> Tail.
Your results are actually correct in both cases. The unexpected string in the first case is due to the fact that in Erlang strings are just lists of integers. Therefore, Erlang chooses to interpret your first list as a string, since it contains only printable ASCII codes. In the second case the list contains the code 7, which is not printable, so Erlang is forced to interpret it as an integer list.
You can always print the actual integer list by using
MyList = lists:dropwhile(fun(X) -> X < 8 end, lists:seq(1,10)),
io:format("~w", [MyList]).
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