Boost 库 write_json 在末尾添加额外的新行

Question

我正在向 http://www.cochoy.fr/boost-property-tree/ 学习。我试图将它保存在一个字符串中，而不是 write_json 到标准输出。

std::stringstream  ss;
boost::property_tree::json_parser::write_json(ss, oroot, false);
std::cout <<" begin json string" << std::endl;
std::cout << ss.str() << std::endl;
std::cout << "after json string" << std::endl;

输出：

 begin json string
{"height":"320","some":{"complex":{"path":"bonjour"}},"animals":{"rabbit":"white","dog":"brown","cat":"grey"},"fish":"blue","fish":"yellow","fruits":["apple","raspberry","orange"],"matrix":[["1","2","3"],["4","5","6"],["7","8","9"]]}

after json string

根据上面的输出，末尾有一个新的空行。如何摆脱新线？因为新行不是有效的 JSON 字符串。

Answer 1

JSON RFC-7159 but it is defined as part of the POSIX standard for a line中没有明确提到换行符。

如果您对换行符的来源感兴趣，可以查看 write_json_internal source code，我们可以看到在方法末尾附近有一个 stream << std::endl;。请注意 ...::write_json 引用 write_json_internal.

 // Write ptree to json stream
template<class Ptree>
void write_json_internal(std::basic_ostream<typename Ptree::key_type::value_type> &stream, 
                         const Ptree &pt,
                         const std::string &filename,
                         bool pretty)
{
    if (!verify_json(pt, 0))
        BOOST_PROPERTY_TREE_THROW(json_parser_error("ptree contains data that cannot be represented in JSON format", filename, 0));
    write_json_helper(stream, pt, 0, pretty);
    stream << std::endl;
    if (!stream.good())
        BOOST_PROPERTY_TREE_THROW(json_parser_error("write error", filename, 0));
}

Boost 库 write_json 在末尾添加额外的新行

Boost library write_json put extra new line at the end

json

boost