Question

I asked this question before but with less information than I have now.

What I essentially have is a data block of type char. That block contains filenames that I need to format and put into a vector. I initially thought the formation of this char block had three spaces between each filename. Now, I realize they are ‘/0’ null terminated characters. So the solution that was provided was fantastic for the example I gave when I thought that there were spaces rather than null chars.

Here is what the structure looks like. Also, I should point out I DO have the size of the character data block.

filename1.bmp/0/0/0brick.bmp/0/0/0toothpaste.gif/0/0/0

The way the best solution did it was this:

// The stringstream will do the dirty work and deal with the spaces.
   std::istringstream iss(s);

   // Your filenames will be put into this vector.
   std::vector<std::string> v;

   // Copy every filename to a vector.
   std::copy(std::istream_iterator<std::string>(iss),
    std::istream_iterator<std::string>(),
    std::back_inserter(v));

   // They are now in the vector, print them or do whatever you want with them!
   for(int i = 0; i < v.size(); ++i)
    std::cout << v[i] << "\n"; 

This works fantastic for my original question but not with the fact they are null chars instead of spaces. Is there any way to make the above example work. I tried replacing null chars in the array with spaces but that didn’t work.

Any ideas on the best way to format this char block into a vector of strings?

Thanks.

Answer 1

If you know your filenames don’t have embedded “\0” characters in them, then this should work. (untested)

const char * buffer = "filename1.bmp/0/0/0brick.bmp/0/0/0toothpaste.gif/0/0/0";
int size_of_buffer = 1234; //Or whatever the real value is

const char * end_of_buffer = buffer + size_of_buffer;

std::vector<std::string> v;

while( buffer!=end_of_buffer)
{
  v.push_back( std::string(buffer) );
  buffer = buffer+filename1.size()+3;
}

If they do have embedded null characters in the filename you’ll need to be a little cleverer.
Something like this should work. (untested)

char * start_of_filename = buffer;
while( start_of_filename != end_of_buffer )
{

  //Create a cursor at the current spot and move cursor until we hit three nulls
  char * scan_cursor = buffer;
  while( scan_cursor[0]!='\0' && scan_cursor[1]!='\0' && scan_cursor[2]!='\0' )
  {
     ++scan_cursor;
  }

  //From our start to the cursor is our word.
  v.push_back( std::string(start_of_filename,scan_cursor) );

  //Move on to the next word
  start_of_filename = scan_cursor+3;
}