Could anyone help? Why the below code will crash on the below line? I'm using the boost property_tree. Thanks. child1.get().put(sub_field, strValue); ========================================================= #include <fstream> #include <boost/filesystem.hpp> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/ini_parser.hpp> #include <boost/any.hpp> #include <boost/optional.hpp> void writeConfig(const std::string &field, const std::string &sub_field, const std::string & strValue) { if (!boost::filesystem::exists(prog_cfg_file)) { std::ofstream ofIniConfig(prog_cfg_file, std::ofstream::out|std::ofstream::app); ofIniConfig.close(); } boost::property_tree::ptree pt; boost::property_tree::ini_parser::read_ini(prog_cfg_file, pt); boost::optional<boost::property_tree::ptree&> child1 = pt.get_child_optional(field); if (child1) { boost::optional<boost::property_tree::ptree&> child2 = child1.get().get_child_optional(sub_field); if (child2) { child2.get().put_value(strValue); }else { child2.get().put_value(strValue); } }else { child1.get().put(sub_field, strValue); } boost::property_tree::ini_parser::write_ini(prog_cfg_file, pt); } int main() { writeConfig("test", "a", "OK"); return 0; } -- 兰生幽谷, 不以无人而不芳...