使用boost读取json文件
使用boost读取json文件
提问于 2013-03-05 00:53:03
我有一个这样的文件：
data.json
{
"electron": {
"pos": [0,0,0],
"vel": [0,0,0]
},
"proton": {
"pos": [1,0,0],
"vel": [0,0.1,0]
},
"proton": {
"pos": [-1,0,0],
"vel": [0,-0.1,-0.1]
}
}如何通过解析此文件来创建粒子矢量。据我所知，我需要使用boost读取文件，并将字符串(行)读入向量，然后解析向量的内容。
类粒子是这样的：
class Particle
{
private:
particle_type mtype; // particle_type is an enum
vector<double> mPos;
vector<double> mVel;
};get/set的其他方法在类中被省略了。
基本上，我希望帮助创建一个正确的位置和速度数据和particle_type数据解析到它的vector<Particle>。提前谢谢。
main中的代码：
int main(){
boost::property_tree::ptree pt;
boost::property_tree::read_json("data.json", pt);
}回答 3
Stack Overflow用户
发布于 2013-03-05 01:09:54
我稍微修改了一下你的JSON。稍微未经测试的代码。
{
"particles": [
{
"electron": {
"pos": [
0,
0,
0
],
"vel": [
0,
0,
0
]
},
"proton": {
"pos": [
-1,
0,
0
],
"vel": [
0,
-0.1,
-0.1
]
}
}
]
}..。
#ifdef _MSC_VER
#include <boost/config/compiler/visualc.hpp>
#endif
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/foreach.hpp>
#include <cassert>
#include <exception>
#include <iostream>
#include <sstream>
#include <string>
int main()
{
try
{
std::stringstream ss;
// send your JSON above to the parser below, but populate ss first
boost::property_tree::ptree pt;
boost::property_tree::read_json(ss, pt);
BOOST_FOREACH(boost::property_tree::ptree::value_type &v, pt.get_child("particles.electron"))
{
assert(v.first.empty()); // array elements have no names
std::cout << v.second.data() << std::endl;
// etc
}
return EXIT_SUCCESS;
}
catch (std::exception const& e)
{
std::cerr << e.what() << std::endl;
}
return EXIT_FAILURE;
}按您认为合适的方式修改。
打印整个树以查看正在读取的内容。这有助于调试。
void print(boost::property_tree::ptree const& pt)
{
using boost::property_tree::ptree;
ptree::const_iterator end = pt.end();
for (ptree::const_iterator it = pt.begin(); it != end; ++it) {
std::cout << it->first << ": " << it->second.get_value<std::string>() << std::endl;
print(it->second);
}
}Stack Overflow用户
发布于 2013-03-05 01:04:15
您可以使用以下代码进行迭代：
boost::property_tree::basic_ptree<std::string,std::string>::const_iterator iter = pt.begin(),iterEnd = pt.end();
for(;iter != iterEnd;++iter)
{
iter->first; // Your key, at this level it will be "electron", "proton", "proton"
iter->second; // The object at each step {"pos": [0,0,0], "vel": [0,0,0]}, etc.
}希望能有所帮助
Stack Overflow用户
发布于 2017-03-22 05:38:43
我只是在更正上面答案的问题，但我无法在评论中获得正确的格式：
#ifdef _MSC_VER
#include <boost/config/compiler/visualc.hpp>
#endif
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <boost/foreach.hpp>
#include <cassert>
#include <exception>
#include <iostream>
#include <sstream>
#include <string>
void print(boost::property_tree::ptree const& pt)
{
using boost::property_tree::ptree;
ptree::const_iterator end = pt.end();
for (ptree::const_iterator it = pt.begin(); it != end; ++it) {
std::cout << it->first << ": " << it->second.get_value<std::string>() << std::endl;
print(it->second);
}
}
int main()
{
try
{
std::stringstream ss;
// send your JSON above to the parser below, but populate ss first
ss << "{ \"particles\": [ { \"electron\": { \"pos\": [ 0, 0, 0 ], \"vel\": [ 0, 0, 0 ] }, \"proton\": { \"pos\": [ -1, 0, 0 ], \"vel\": [ 0, -0.1, -0.1 ] } } ]}";
boost::property_tree::ptree pt;
boost::property_tree::read_json(ss, pt);
BOOST_FOREACH(boost::property_tree::ptree::value_type &v, pt.get_child("particles"))
{
assert(v.first.empty()); // array elements have no names
print(v.second);
}
return EXIT_SUCCESS;
}
catch (std::exception const& e)
{
std::cerr << e.what() << std::endl;
}
return EXIT_FAILURE;
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/15206705
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