How to format a number with padding in Erlang

Question

I need to pad the output of an integer to a given length.

For example, with a length of 4 digits, the output of the integer 4 is "0004" instead of "4". How can I do this in Erlang?

Answer 1

io:format("~4..0B~n", [Num]).

Answer 2

string:right(integer_to_list(4), 4, $0).