Re: [Boost-users] How to use the optional with property_tree‏

Subject: Re: [Boost-users] How to use the optional with property_tree‏
From: Olivier Tristan (o.tristan_at_[hidden])
Date: 2013-12-19 09:07:49

Those following lines from your code should give you a hint

if (child2)
{
child2.get().put_value(strValue);
}
else
{
child2.get().put_value(strValue);
}

Le 19/12/2013 12:34, 王郁槐 a écrit :
> 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, ä¸ä»¥æ— äººè€Œä¸èŠ³...
>
>
>
>
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-- 
Olivier TRISTAN
uvi.net