将字节写入.Bin文件

Question

I have a vector in C++ that I want to write it to a .bin file. this vector's type is byte , and the number of bytes could be huge, maybe millions. I am doing it like this:

if (depthQueue.empty())
    return;

FILE* pFiledep;

pFiledep = fopen("depth.bin", "wb");

if (pFiledep == NULL)
    return;

byte* depthbuff = (byte*) malloc(depthQueue.size() * 320 * 240 * sizeof(byte));

if(depthbuff)
{
  for(int m = 0; m < depthQueue.size(); m++)
  {
    byte b = depthQueue[m];
    depthbuff[m] = b;
  }

  fwrite(depthbuff, sizeof(byte),
        depthQueue.size() * 320 * 240 * sizeof(byte), pFiledep);
  fclose(pFiledep);
  free(depthbuff);
}

depthQueue is my vector which contains bytes and lets say its size is 100,000.
Sometimes I don't get this error, but the bin file is empty.
Sometime I get heap error.
Somtimes when I debug this, it seems that malloc doesn't allocate the space. Is the problem is with space?

Or is chunk of sequential memory is so long and it can't write in bin?

Answer 1

You don't need hardly any of that. vector contents are guaranteed to be contiguous in memory, so you can just write from it directly:

fwrite(&depthQueue[0], sizeof (Byte), depthQueue.size(), pFiledep);

Note a possible bug in your code: if the vector is indeed vector<Byte> , then you should not be multiplying its size by 320*240.

EDIT: More fixes to the fwrite() call: The 2nd parameter already contains the sizeof (Byte) factor, so don't do that multiplication again in the 3rd parameter either (even though sizeof (Byte) is probably 1 so it doesn't matter).