Erlang and OTP in Action.pdf - Synrc

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For division, there are two choices. First, the / operator always yields a floating point
number, so for example 4/2 yields 2.0, not 2. Integer division (truncating) is performed by
the div operator, as in 7 div 2, yielding 3.
The remainder of an integer division is given by the rem operator, as in 15 rem 4,
yielding 3. (This can differ from what a “modulo” operator would yield, if negative numbers
are involved.)
Other floating-point arithmetic functions are found in the standard library module math;
these are named directly after the corresponding functions in the C standard library, for
example math:sqrt(2).
There are also some additional integer operators for bitwise operations: N bsl K shifts
the integer N K steps to the left, and bsr performs a corresponding arithmetic right shift.
The bitwise logic operators are named band, bor, bxor, and bnot. For example, X band
(bnot Y) would mask away those bits from X that are set in Y.
From numerical data, let’s move on to something equally primitive: bits and bytes.
2.2.2 – Binaries and bitstrings
A binary is a sequence of unsigned 8-bit bytes, used for storing and processing chunks of
data (often data that comes from a file or has been received over some network protocol). A
bitstring is a generalized binary whose length in bits is not necessarily a multiple of 8; it
could for instance be 12 bits long, consisting of “one and a half” bytes.
Arbitrary bitstrings are a more recent addition to the language, while whole-byte binaries
have been around for many years, but to a programmer there is very little difference on the
surface of things, except that you can do some really nifty things these days that used to be
impossible before. Since the syntax is the same, and the name “binary” is so ingrained, you
rarely hear people (including us) talk about “bitstrings” unless they want to make a point
about the more flexible length.
The basic syntax for a binary is:
that is, a comma-separated list of integers in the range 0 to 255, enclosed in >. There
must not be any space between the two delimiter characters on either side, as in “<