C++ stringT::substr方法代码示例

int CXMLprefs::SetPreference(const stringT &sPath, const stringT &sValue)
{
  // Find the node specified by the path, creating it if it does not already exist
  // and add the requested value.

  // Notes:
  // This routine only adds plain character data to the node, see comments at the end.
  // If the node already has plain character data, it is replaced.
  // If the node exists multiple times with the same path, only the first is altered -
  //   see description of function "first_element_by_path" in the pugixml manual.

  int iRetVal = XML_SUCCESS;
  
  // First see if the node already exists
  pugi::xml_node node = m_pXMLDoc->first_element_by_path(sPath.c_str(), _T('\\'));
  
  if (node == NULL) {
    // Not there - let's build it
    // Split up path and then add all nodes in the path (if they don't exist)
    // Start at the top
    node = m_pXMLDoc->root();
  
    stringT::size_type pos, lastPos(0);

    // Find first "non-delimiter".
    pos = sPath.find_first_of(_T('\\'), lastPos);

    // Get all nodes in the path, if they exist fine, if not, create them
    while (pos != stringT::npos || lastPos != stringT::npos) {
      // Retrieve next node name from path
      stringT snode = sPath.substr(lastPos, pos - lastPos);
      
      // Try to get it
      pugi::xml_node child = node.child(snode.c_str());

      // If not there, add it otherwise use it for the next iteration
      node = (child == NULL) ? node.append_child(snode.c_str()) : child;
    
      // Skip delimiter and find next "non-delimiter"
      lastPos = sPath.find_first_not_of(_T('\\'), pos);
      pos = sPath.find_first_of(_T('\\'), lastPos);
    }
  }

  //  ***** VERY IMPORTANT *****
  // Note, as documented in the pugi manual under "Document object model/Tree Structure",
  // nodes can be of various types.  Element nodes found above, do not have a value.
  // To add a value to an element node, one has to add a child node of type
  // 'node_pcdata' (plain character data node) or 'node_cdata' (character data node),
  // the latter using <![CDATA[[...]]> to encapsulate the data.

  // If the node has data in its first pcdata child use it, otherwise add a pcdata child
  pugi::xml_node prefnode = (node.first_child().type() == pugi::node_pcdata) ?
     node.first_child() : node.append_child(pugi::node_pcdata);

  if (!prefnode.set_value(sValue.c_str()))
     iRetVal = XML_PUT_TEXT_FAILED;

  return iRetVal;
}

  // In following, drive will be empty on non-Windows platforms
bool pws_os::splitpath(const stringT &path,
                       stringT &drive, stringT &dir,
                       stringT &file, stringT &ext)
{
  if (path.empty())
    return false;
  drive = _T("");
  stringT::size_type last_slash = path.find_last_of(_T("/"));
  dir = path.substr(0, last_slash + 1);
  stringT::size_type last_dot = path.find_last_of(_T("."));
  if (last_dot != stringT::npos && last_dot > last_slash) {
    file = path.substr(last_slash + 1, last_dot - last_slash - 1);
    ext = path.substr(last_dot + 1);
  } else {
    file = path.substr(last_slash + 1);
    ext = _T("");
  }
  return true;
}