бинарные файлы

//Streams were originally designed for text, so the default

//output mode is text.

//In text mode, the newline character

//(hexadecimal 10) expands

//to a carriage return–linefeed (16-bit only).

//The expansion can cause problems, as shown here:

// binary_output_files.cpp
// compile with: /EHsc
#include <fstream>
using namespace std;
int iarray[2] = { 99, 10 };
int main( )
{
    ofstream os( "test.dat" );
    os.write( (char *) iarray, sizeof( iarray ) );
}

//You might expect this program to output the byte sequence

//{ 99, 0, 10, 0 };

//instead, it outputs { 99, 0, 13, 10, 0 },which causes

//problems for a program expecting binary input.

//If you need true binary output, in which characters are

//written untranslated, you could specify binary output by

//using the ofstream constructor mode argument:

// binary_output_files2.cpp
// compile with: /EHsc
#include <fstream>
using namespace std;
int iarray[2] = { 99, 10 };

int main()
{
   ofstream ofs ( "test.dat", ios_base::binary );

   // Exactly 8 bytes written
   ofs.write( (char*)&iarray[0], sizeof(int)*2 );
}
See Also
Output Streams