C++ Json-cpp - 如何从字符串初始化并获取字符串值？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/31121378/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Json-cpp - how to initialize from string and get string value?
提问by Greyshack
My code below crashes(Debug Error! R6010 abort() has been called). Can you help me? I'd also would like to know how to initialize the json object from a string value.
我下面的代码崩溃了（调试错误！R6010 abort() 已被调用）。你能帮助我吗？我还想知道如何从字符串值初始化 json 对象。
Json::Value obj;
obj["test"] = 5;
obj["testsd"] = 655;
string c = obj.asString();
回答by Irineu Antunes
Hello it is pretty simple:
你好，很简单：
1 - You need a CPP JSON value object (Json::Value) to store your data
1 - 您需要一个 CPP JSON 值对象 (Json::Value) 来存储您的数据
2 - Use a Json Reader (Json::Reader) to read a JSON String and parse into a JSON Object
2 - 使用 Json Reader (Json::Reader) 读取 JSON 字符串并解析为 JSON 对象
3 - Do your Stuff :)
3 - 做你的事:)
Here is a simple code to make those steps:
这是一个简单的代码来完成这些步骤：
#include <stdio.h>
#include <jsoncpp/json/json.h>
#include <jsoncpp/json/reader.h>
#include <jsoncpp/json/writer.h>
#include <jsoncpp/json/value.h>
#include <string>
int main( int argc, const char* argv[] )
{
std::string strJson = "{\"mykey\" : \"myvalue\"}"; // need escape the quotes
Json::Value root;
Json::Reader reader;
bool parsingSuccessful = reader.parse( strJson.c_str(), root ); //parse process
if ( !parsingSuccessful )
{
std::cout << "Failed to parse"
<< reader.getFormattedErrorMessages();
return 0;
}
std::cout << root.get("mykey", "A Default Value if not exists" ).asString() << std::endl;
return 0;
}
To compile: g++ YourMainFile.cpp -o main -l jsoncpp
编译： g++ YourMainFile.cpp -o main -l jsoncpp
I hope it helps ;)
我希望它有帮助;)
回答by mts knn
Json::Readeris deprecated, as stated in the documentation. Here's how to use Json::CharReaderand Json::CharReaderBuilder:
Json::Reader已弃用，如文档中所述。以下是如何使用Json::CharReader和Json::CharReaderBuilder：
std::string strJson = R"({"foo": "bar"})";
Json::CharReaderBuilder builder;
Json::CharReader* reader = builder.newCharReader();
Json::Value json;
std::string errors;
bool parsingSuccessful = reader->parse(
strJson.c_str(),
strJson.c_str() + strJson.size(),
&json,
&errors
);
delete reader;
if (!parsingSuccessful) {
std::cout << "Failed to parse the JSON, errors:" << std::endl;
std::cout << errors << std::endl;
return;
}
std::cout << json.get("foo", "default value").asString() << std::endl;
Kudos to p-a-o-l-o for their answer here: Parsing JSON string with jsoncpp
感谢 paolo 的回答：Parsing JSON string with jsoncpp
