[C++] problem z binarnimi datotekami

tole je s spleta....pri meni pa je kot sem omenil!
Kakšen nasvet? Se že mučim dve uri...! :)

p.s.
kako popravim naslov teme? Namreč rad bi dodal še: "... (write binary file)"

// crt__write.c
// 
// This program opens a file for output and uses _write to write
// some bytes to the file.

#include <io.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <share.h>

char buffer[] = "This is a test of '_write' function";

int main( void )
{
   int         fileHandle = 0;
   unsigned    bytesWritten = 0;

   if ( _sopen_s(&fileHandle, "write.o", _O_RDWR | _O_CREAT,
                  _SH_DENYNO, _S_IREAD | _S_IWRITE) )
      return -1;

   if (( bytesWritten = _write( fileHandle, buffer, sizeof( buffer ))) == -1 )
   {
      switch(errno)
      {
         case EBADF:
            perror("Bad file descriptor!");
            break;
         case ENOSPC:
            perror("No space left on device!");
            break;
         case EINVAL:
            perror("Invalid parameter: buffer was NULL!");
            break;
         default:
            // An unrelated error occured 
            perror("Unexpected error!");
      }
   }
   else
   {
      printf_s( "Wrote %u bytes to file.\n", bytesWritten );
   }
   _close( fileHandle );
}

#define _SizeOfRxBuffer_		1024
unsigned char RxBuffer[_SizeOfRxBuffer_];	//1kB=0x400=1024 sectors: 0x000..0x3FF, 0x400..0x7FF, 0x800..0xBFF, 0xC00..0xFFF

unsigned int Count_OKbytes;
char	*imeOutFile="RxBuffer.txt";
int SaveBuff2File(unsigned char *Save_buffer,char *imeOUTf,unsigned int NoOfBytes);

//==========================================================================================
//	main
//==========================================================================================
int main( int argc, // Number of strings in array argv
 char *argv[])		// Array of command-line argument strings )
{
.......

	returnStatus=SaveBuff2File(RxBuffer, imeOutFile, Count_OKbytes);	//save buffer to file

.......
}



//-------------------------------------------------------------------------
/* write binary data from buffer to filee */
int SaveBuff2File(unsigned char *Save_buffer,char *imeOUTf,unsigned int NoOfBytes)
{
   int         fileHandle = 0;
   unsigned    bytesWritten = 0;

   if ( _sopen_s(&fileHandle, imeOUTf, _O_WRONLY | _O_CREAT,	_SH_DENYRD,	_S_IREAD) )
      return -1;
	

   if (( bytesWritten = _write( fileHandle, Save_buffer, sizeof(Save_buffer) )) == -1 )
   {
      switch(errno)
      {
         case EBADF:
            perror("Bad file descriptor!");
            break;
         case ENOSPC:
            perror("No space left on device!");
            break;
         case EINVAL:
            perror("Invalid parameter: buffer was NULL!");
            break;
         default:
            // An unrelated error occured 
            perror("Unexpected error!");
      }
   }
   else
   {
      printf_s( "Wrote %u bytes to file: %s\n", bytesWritten, imeOUTf);
   }
   _close( fileHandle );
   return 0;
}

HVALA za odgovore!

sem spremenil na:

int SaveBuff2File(unsigned char *Save_buffer,char *imeOUTf)
{......
   if (( bytesWritten = _write( fileHandle, Save_buffer, sizeof(Save_buffer) )) == -1 )
......
}

tako, da mi znotraj funkcije izračuna velikost bufferja, ki se bo zapisal v file!


Kako pa naredim, da se file izbriše in nato vpiše buffer v file (rewrite)?
Torej vedno imam samo pisanje (rewrite)(najprej brisanje nato pa vpis)!
Katere FLAG-e nastavit?

   if ( _sopen_s(&fileHandle, imeOUTf, _O_WRONLY | _O_CREAT,	_SH_DENYNO,		_S_IREAD | _S_IWRITE) )
      return -1;	

Namreč sedaj mi file pusti in npr. če je buffer "1234" pusti vse kot je samo na začetku vpiše 1234

v arrayeu oz. RxBuffer-ju so štirje byte-i, array do konca je zafilan z 0x00
Če dam sizeof(*Save_buffer)
mi zapiše v file samo 1.byte!
:(


_O_TRUNC flag mi vedno samo briše in nič ne zapiše!
(to bom nekako reši, da bom najprej file zbrisal pa nato vpisal nov file)

Poženi tole:

#include <iostream>

void foo(char* buf)
{
    std::cout << sizeof(buf) << '\n'
              << sizeof(*buf);
}

int main()
{
    char buf[] = "zapis si za uhelj: arrayi niso pointerji.";
    std::cout << sizeof(buf) << '\n';
    foo(buf);
}

pa boš upam dojel, v čem se tvoja koda razlikuje od tiste z MSDN-a.

Array, dokler si v scope-u v katerem je definiran, nosi podatek o svoji velikosti (sizeof vrne število elementov krat sizeof enega elementa). Se pa, ko ga pošlješ kot argument fukciji, implicitno pretvori v kazalec na prvi element in takrat pač ni več array.