C++ istream::width方法代码示例

int Narf::loadHeader(std::istream& file) const
{
  size_t pos_in_file = file.tellg();
  file.width(getHeaderKeyword().size()+10); // limit maximum number of bytes to read
  std::string header;
  file >> header;
  file.width(0); // remove limit
  if (header != getHeaderKeyword())
  {
    file.seekg(pos_in_file);  // Go back to former pos in file
    return -1;
  }
  int version;
  file >> version;
  file.ignore(1);  // Skip the space after the version number
  
  return version;
}

// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
int32_t VtkStructuredPointsReader::readString(std::istream& in, char* result, size_t length)
{
  in.width(length);
  in >> result;
  if (in.fail())
  {
    return 0;
  }
  return 1;
}

unsigned int eft::readPTXM( std::istream &file )
{
    unsigned int ptxmSize;
    unsigned int total = readFormHeader( file, "PTXM", ptxmSize );
    ptxmSize += 8;
    std::cout << "Found FORM PTXM: " << ptxmSize-12 << " bytes"
	      << std::endl;

    unsigned int size;
    std::string type;
    total += readRecordHeader( file, type, size );
#if 0
    if( type != "0002" )
    {
        std::cout << "Expected record of type 0002: " << type << std::endl;
        throw std::exception();
    }
#endif
    std::cout << "Found record " << type
	      << ": " << size << " bytes"
	      << std::endl;

    std::string name;
    unsigned char num;
    total += base::read( file, num );
#if 1
    file.width( size - sizeof( unsigned char ) );
    file >> name;
    total += size;
#else
    total += base::read( file, name );
#endif
    std::cout << "Pixel shader texture " << (unsigned int)num
	      << ": " << name << std::endl;

    if( ptxmSize == total )
    {
	std::cout << "Finished reading PTXM" << std::endl;
    }
    else
    {
	std::cout << "FAILED in reading PTXM" << std::endl;
	std::cout << "Read " << total << " out of " << ptxmSize
                  << std::endl;
    }

    return total;
}

// Read name-value pairs from the stream.  If the first item is a number, then
// we expect that many name-value pairs.  If not, then we read until the end of
// the stream.  Be sure not to duplicate the last one, and be sure to dump any
// items from a # to end-of-line.
//   Parse for name-value pairs, where the pairs are separated by whitespace.
// *Every* parameter must be specified as a name-value pair (no single name 
// with no value allowed).  If we get a single name with no value that will
// screw up the name-value pairing for any remaining pairs.  We could check for
// this situation, but for now we just let it happen and dump the errors. (i'll
// do a better parsing algorithm at some later point).
//   We return the number of items that we were able to read from the stream.
// If we come across an item that is unrecognized, we dump an error message.
//   The buffer length is limited here, so don't try to read in any really long
// lines.
//   We parse only for items that we know about - if we come across a pair
// whose name we do not know about, we ignore the pair and go on to the next.
// There's no global list to tell us what type things are, and we don't assume.
//   We don't allow setting pointers using this method.
int
GAParameterList::read(std::istream& is, GABoolean flag){
  int nfound = 0;
  if(n == 0) return nfound;

  char buf[BUFSIZE];
  char name[NAMESIZE];
  int toggle = 0, count = 0, npairs = -1;

  is.width(sizeof(buf));	// don't allow to overrun buffer

  do{
    is >> buf;
    if(npairs == -1){
      if(IsNumeric(buf)){
	npairs = atoi(buf);
	is >> buf;
      }
      else{
	npairs = MAX_PAIRS;
      }
    }
    if(is.eof()){
      break;
    }
    else if(buf[0] == '#'){		// dump to end-of-line
      is.get(buf, BUFSIZE);		// fails on lines longer than BUFSIZE
    }
    else if(toggle == 0){
      strcpy(name, buf);
      toggle = 1;
    }
    else if(toggle == 1){
      int found = 0;

      count += 1;
      toggle = 0;

      for(unsigned int i=0; i<n && !found; i++){
	if(strcmp(name, p[i]->fullname()) == 0 ||
	   strcmp(name, p[i]->shrtname()) == 0){
	  found = 1;

	  int ival;
	  float fval;
	  double dval;
	  
	  switch(p[i]->type()){
	  case GAParameter::BOOLEAN:
	  case GAParameter::INT:
	    ival = atoi(buf);
	    set(name, (void*)&ival);
	    nfound += 1;
	    break;
	  case GAParameter::CHAR:
	  case GAParameter::STRING:
	    set(name, (void*)buf);
	    nfound += 1;
	    break;
	  case GAParameter::FLOAT:
	    fval = (float)atof(buf);
	    set(name, (void*)&fval);
	    nfound += 1;
	    break;
	  case GAParameter::DOUBLE:
	    dval = (double)atof(buf);
	    set(name, (void*)&dval);
	    nfound += 1;
	    break;
	  case GAParameter::POINTER:
	  default:
	    break;
	  }

// Move this parameter to the front of the list

//	  if(i > 0) {
//	    GAParameter *tmpptr = p[i];
//	    memmove(&(p[1]), &(p[0]), i * sizeof(GAParameter*));
//	    p[0] = tmpptr;
//	  }
	  if(i < n-1) {
//.........这里部分代码省略.........