c++ - libconfig++ : adding a setting to the root of the configuration tree -

i have configuration file mycfg.cfg looks :

keya = 1.0 keyb = 2 keyc = "hello" 

note settings @ root of configuration tree.

i want c++ program load file add new setting key keyd , assign integer value 5. eventually, mycfg should in memory :

keya = 1.0 keyb = 2 keyc = "hello" keyd = 5 

first mycfg.cfg file loaded construct mycfg. setting keyd must added root of mycfg. libconfig documentation indicates setting::add() method :

add[s] new child setting given name , type setting, must group

however, there isn't group in mycfg… how add setting root of config object ?

it looks need is: getroot ().

here example:

#include <iostream> #include "libconfig.h++"   int main () {     libconfig::config mycfg;     std::string file = "mycfg.cfg";      try {         mycfg.readfile (file.c_str () );          libconfig::setting & root = mycfg.getroot ();         // works.         // libconfig::setting & root = mycfg.lookup ("");         libconfig::setting & keyd = root.add ("keyd", libconfig::setting::typeint);         keyd = 5;          // dont need it, it's testing.         mycfg.writefile (file.c_str () );     }     catch (...) {         std::cout << "error caused!" << std::endl;     }      return 0; }