How to write information to a file in binary form

yisinio

I want to write unsigned long data to a file in binary, knowing the number of bits required for each data (BIT, that is, just writing N bits).
I did this but no data was written.
ifstream in ("test.txt"); // where are the characters
ofstream out;
out.open ("result.xxx", ios :: binary);

int index;

while (! in.eof ())
{
in >> index;
out.write ((char *) (code [index]), code_len [index]);
}

gogoandsoso

out.write ((char *) (code [index]), code_len [index]);
----------------------------
What is code? What's in it?

yisinio

code is unsigned long

boxer2005

Write a multi-byte data to a file and then recover it from the file. This method has portability problems, because different platforms have different byte ordering methods (big-endian and little-endian). A unified format (define a sequence by yourself, or use network byte order) conventions, so that can be.

zjwzjw

BIT, that is, just write N bits
==========
The basic unit of reading and writing files is bytes. It is not possible to write only a few bits.
Only whole bytes can be written to the file ~~~

zjwzjw

// Test it with a simple program first

char str [] = "Hello, Boy!";

ofstream out;
out.open ("result.txt", ios :: binary);
out.write (str, strlen (str)); // Write file
out.close (); // close

killerss

>> The landlord needs to make a convention in a unified format (define a sequence by himself or use the network byte order), so that can be done.

XDR ...

qtfjkmh

The operations on files are in bytes. The landlord does not want to operate on files in bits.