Integer to Binary Erlang

问题

I am trying to make an integer into a binary:

543 = <<"543">>

How can I do this without

integer_to_list(list_to_binary(K)).

回答1:

If you want to convert 543 to <<"543">> I don't think you can find something faster than:

1> list_to_binary(integer_to_list(543)).
<<"543">>

Because in this case both functions implemented in C.

If you want to convert integer to the smallest possible binary representation you can use binary:encode_unsigned function from the new binary module like this:

1> binary:encode_unsigned(543).
<<2,31>>
2> binary:encode_unsigned(543, little).
<<31,2>>

回答2:

For current readers, this is now implemented in R16, see http://erlang.org/doc/man/erlang.html#integer_to_binary-1

回答3:

You can try something like

6> A = 12345.                       
12345
7> B = <<A:32>>.
<<0,0,48,57>>

But this requires you to know the maximum number of bits in advance.

来源：https://stackoverflow.com/questions/4010713/integer-to-binary-erlang