\Header{readBin}{Transfer Binary Data To and From Connections}
\alias{writeBin}{readBin}
\keyword{file}{readBin}
\keyword{connection}{readBin}
\begin{Description}\relax
Read binary data from a connection, or write binary data to a connection.\end{Description}
\begin{Usage}
\begin{verbatim}
readBin(con, what, n = 1, size = NA, endian = .Platform$endian)
writeBin(object, con, size = NA, endian = .Platform$endian)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{con}] A connection object or a character string.
\item[\code{what}] Either an object whose mode will give the mode of the
vector to be read, or a character vector of length one describing
the mode: one of \code{"numeric", "double", "integer", "int",
      "logical", "complex", "character"}.
\item[\code{n}] integer.  The (maximal) number of records to be
read. You can use an over-estimate here, but not too large as
storage is reserved for \code{n} items.
\item[\code{size}] integer.  The number of bytes per element in the byte
stream.  The default, \code{NA}, uses the natural size.  Size changing
is not supported for complex vectors.
\item[\code{endian}] The endian-ness (\code{"big"} or \code{"little"} of the
target system for the file.  Using \code{"swap"} will force swapping
endian-ness.
\item[\code{object}] An \R{} object to be written to the connection.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If the \code{con} is a character string, the functions call
\code{\Link{file}} to obtain an file connection which is opened for
the duration of the function call.

If the connection is open it is read/written from its current position.
If it is not open, it is opened for the duration of the call and then
closed again.

If \code{size} is specified and not the natural size of the object,
each element of the vector is coerced to an appropriate type before
being written or as it is read.  Possible sizes are 1, 2, 4 and
possibly 8 for integer or logical vectors, and 4, 8 and possibly 12/16
for numeric vectors.  (Note that coercion occurs as signed types.)
Changing sizes is unlikely to preserve \code{NA}s, and the extended
precision sizes are unlikely to be portable across platforms.\end{Details}
\begin{Value}
For \code{readBin}, a vector of appropriate mode and the number of
items read (which might be less than \code{n}).

For \code{writeBin}, none.\end{Value}
\begin{Note}\relax
Integer read/writes of size 8 will be available if either C type
\code{long} is of size 8 bytes or C type \code{long long} exists and
is of size 8 bytes.

Real read/writes of size \code{sizeof(long double)} (usually 12 or 16
bytes) will be available only if that type is available and different
from \code{double}.\end{Note}
\begin{SeeAlso}\relax
\code{\Link{connection}}, \code{\Link{readLines}}, \code{\Link{writeLines}}\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
zz <- file("testbin", "wb")
writeBin(1:10, zz)
writeBin(pi, zz, endian="swap")
writeBin(pi, zz, size=4)
writeBin(pi^2, zz, size=4, endian="swap")
writeBin(pi+3i, zz)
writeBin("A test of a connection", zz)
z <- paste("A very long string", 1:100, collapse=" + ")
writeBin(z, zz)
close(zz)

zz <- file("testbin", "rb")
readBin(zz, integer(), 4)
readBin(zz, integer(), 6)
readBin(zz, numeric(), 1, endian="swap")
readBin(zz, numeric(), size=4)
readBin(zz, numeric(), size=4, endian="swap")
readBin(zz, complex(), 1)
readBin(zz, character(), 1)
z2 <- readBin(zz, character(), 1)
close(zz)
unlink("testbin")
stopifnot(z2 == z)
\end{ExampleCode}
\end{Examples}

