jsoncpp 简单示例

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;





原文详见于：http://jsoncpp.sourceforge.net/