我正在使用NLHHMAN的JSON库来与C++中的JSON对象一起工作.最后，我想从一个文件中读取一个json对象，例如这样一个简单的对象.
{
"happy": true,
"pi": 3.141
}
I'm not quite sure how to approach this. At https://github.com/nlohmann several ways are given to deserialise from a string literal, however it doesn't seem trivial to extend this to read in a file. Does anyone have experience with this?
Since version 3.0, json::json(std::ifstream&) is deprecated. One should use json::parse() instead:
std::ifstream ifs("test.json");
json jf = json::parse(ifs);
std::string str(R"({"json": "beta"})");
json js = json::parse(str);
有关如何使用nlohmann的json库的更多基本信息，请参阅nlohmann FAQ.
从version 2.0年到json::operator>>() id deprecated年.人们应该使用json::json()来代替:
std::ifstream ifs("{\"json\": true}");
json j(ifs);
使用json::operator>>(std::istream&):
json j;
std::stringstream ifs("{\"json\": true}");
ifs >> j;