On 24.04.2011 16:12, Beman Dawes wrote:
There have been many requests on Boost and various C++ newsgroups for unformatted binary I/O. For example, in 2003 Neal Becker wrote:
I wonder if anyone has code for implementing unformatted I/O? What I have in mind is for the simple case where the application that reads data knows the data types, so this is not as complicated as the general marshalling situation.
This proposal provides a very simple solution that works with standard library input and output streams. The one caveat is that the stream must be opened with filemode std::ios_base::binary to avoid certain data values being treated as line endings.
int main() { fstream f("binary_stream_example.dat", std::ios_base::trunc | std::ios_base::in | std::ios_base::out | std::ios_base::binary);
int32_t x = 0x01020304; int32_t y = 0;
f<< bin(x); // write 4 bytes f.seekg(0); f>> bin(y); // read 4 bytes
BOOST_ASSERT(x == y);
return 0; }
For docs, header, and example code, see http://mysite.verizon.net/beman/binary_stream/binary_stream.html http://mysite.verizon.net/beman/binary_stream/binary_stream.hpp http://mysite.verizon.net/beman/binary_stream/binary_stream_example.cpp
Is there interest in this for Boost?
It seems way too small and simple to be a whole library itself. Are there any ideas where it should live and what namespace it should be in?
--Beman
For such tasks i use very basic tool in the form of 2 overloaded function templates named raw_cast<>() that converts from native representation of a fundamental type (except void) to its raw-byte representation, and vice versa. raw_cast<>() implementation (raw_cast.hpp): http://codepad.org/x47pQiNA code example: http://codepad.org/5y3RPj9r [output (on a little-endian machine): 67305985 (raw: 1 2 3 4 [little endian]; 4 3 2 1 [big endian]) raw: 0 0 0 0 0 0 f0 3f 7f 0 0 0 58 ff ff ff ff 71 5 0 native: {1 : 127 : X : 0xffffffff : q : 5} --end] (Code works as is on linux. On other platforms there should be defined BYTE_ORDER macro that equals to BIG_ENDIAN or something else; otherwise machine's byte ordering will be interpreted as little endian.) ___________________ I think the following code (used in raw_cast<>() implementation) isn't correct: char const* const begin = reinterpret_cast<char const* const>(&value); char const* const end = reinterpret_cast<char const* const>(&value) + sizeof(T); (Byte representation of any trivial copyable type isn't array actually.) if so, boost::reverse_iterator<> should be replaced below (in code) to an iterator without 'past-the-end' semantics -- - Do you speak English? Мужик с глубоким вздохом: - Yes I do. А хули толку?