jsoncpp 簡單樣本

Here is an example of JSON data:

// Configuration options
{    // Default encoding for text
     "encoding" : "UTF-8",        
  // Plug-ins loaded at start-up
  "plug-ins" : [        "python",        "c++",        "ruby"        ],            
  // Tab indent size    
  "indent" : { "length" : 3, "use_space": true }
}

Code example

Json::Value root; // will contains the root value after parsing.
Json::Reader reader;
bool parsingSuccessful = reader.parse( config_doc, root );

if ( !parsingSuccessful )
{
// report to the user the failure and their locations in the document.
      std::cout  << "Failed to parse configuration\n"               << reader.getFormattedErrorMessages();
   return;
}

// Get the value of the member of root named 'encoding', return 'UTF-8' if there is no
// such member.
  std::string encoding = root.get("encoding", "UTF-8" ).asString();
 // Get the value of the member of root named 'encoding', return a 'null' value if
// there is no such member.
  const Json::Value plugins = root["plug-ins"];

  for ( int index = 0; index < plugins.size(); ++index )  // Iterates over the sequence
   elements.   loadPlugIn( plugins[index].asString() );

  setIndentLength( root["indent"].get("length", 3).asInt() );
  setIndentUseSpace( root["indent"].get("use_space", true).asBool() );
// ...// At application shutdown to make the new configuration document:
// Since Json::Value has implicit constructor for all value types, it is not
// necessary to explicitly construct the Json::Value object:
  root["encoding"] = getCurrentEncoding();
  root["indent"]["length"] = getCurrentIndentLength();
  root["indent"]["use_space"] = getCurrentIndentUseSpace();
  Json::StyledWriter writer;
 // Make a new JSON document for the configuration. Preserve original comments.
  std::string outputConfig = writer.write( root );
 // You can also use streams.  This will put the contents of any JSON
// stream at a particular sub-value, if you'd like.
  std::cin >> root["subtree"];
// And you can write to a stream, using the StyledWriter automatically.
  std::cout << root;


原文詳見於：http://jsoncpp.sourceforge.net/