Unsigned chars

Part of code taken from small JPEG Code Library by Rich Geldreich

bool tga_writer::write_line(const void *Pscan_line)
{
  uchar *Psb = (uchar *)Pscan_line;
      
  if (!Pfile)
    return (true);

  if (fwrite(Pscan_line, bytes_per_line, 1, Pfile) != 1)  // bytes_per_line = 681, in this case
    return (true);

  return (false);
}


// Definition given in header file
typedef unsigned char  uchar;       /*  8 bits     */

in main
=======

uchar *Pdb = Pbuf;

status = Pdst->write_line(Pbuf); // status if of type boolean

My question is
1. how can I assign the contents of Pbuf (within main program) or Pscan_line within

   bool tga_writer::write_line(const void *Pscan_line)

to say an array (1-D or 2-D) so that I can manipulate the contents.