params.json

{
	"driletter": "E",
	"mod": 1,
	"pl": 2,
	"vxmm": 1.1,
	"vymm": 0.5,
	"vzmm": 0.006,
	"nx": 20,
	"ny": 30,
	"zu": 0.600,
	"zl": 0.000,
	"gksize": 17,
	"iothre": 3000
}

ScanParams.h

#pragma once
#include <fstream>

#include "..\picojson.h"

class ScanParams
{
private:
	std::string driletter;
	int mod;
	int pl;
	double vxmm;
	double vymm;
	double vzmm;
	int nx;
	int ny;
	double zu;//upper surface
	double zl;//lower surface
	int gksize;
	int iothre;


public:
	ScanParams(){}
	~ScanParams(){}

	bool ReadJSON(char* jsonname){
		std::ifstream fs;
		fs.open(jsonname, std::ios::binary);
		if (!fs.is_open()) {
			return false;
		}
		picojson::value val;
		fs >> val;
		fs.close();

		driletter = val.get<picojson::object>()["driletter"].get<std::string>();
		mod = int(val.get<picojson::object>()["mod"].get<double>());
		pl = int(val.get<picojson::object>()["pl"].get<double>());
		vxmm = val.get<picojson::object>()["vxmm"].get<double>();
		vymm = val.get<picojson::object>()["vymm"].get<double>();
		vzmm = val.get<picojson::object>()["vzmm"].get<double>();
		nx = int(val.get<picojson::object>()["nx"].get<double>());
		ny = int(val.get<picojson::object>()["ny"].get<double>());
		zu = val.get<picojson::object>()["zu"].get<double>();
		zl = val.get<picojson::object>()["zl"].get<double>();
		gksize = int(val.get<picojson::object>()["gksize"].get<double>());
		iothre = int(val.get<picojson::object>()["iothre"].get<double>());
		return true;
	}

	std::string DriLetter(){return driletter;}
	int MOD(){ return mod; }
	int PL(){ return pl; }
	double VXmm(){ return vxmm; }
	double VYmm(){ return vymm; }
	double VZmm(){ return vzmm; }
	int NX(){ return nx; }
	int NY(){ return ny; }
	int NZ(){ return int((zu-zl)/vzmm); }
	int GKSize(){ return gksize; }
	int IOThre(){ return iothre; }
};

Test_ScanParams.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <string>

#include <assert.h>

#include "ScanParams.h"



int main(int argc, char* argv[]){

	std::cout << "hello" << std::endl;

	//assert(false);

	bool flag;
	ScanParams sp = ScanParams();

	flag = sp.ReadJSON("notexist.json");
	assert(flag == false);


	flag = sp.ReadJSON("params.json");
	assert(flag == true);

	assert(sp.DriLetter() == "E");
	assert(sp.MOD() == 1);
	assert(sp.PL() == 2);
	std::cout << sp.VXmm() << std::endl;

	assert(sp.VXmm() == 1.1);
	assert(sp.NX() == 20);
	assert(sp.NZ() == 100);
	assert(sp.GKSize() == 17);
	assert(sp.IOThre() == 3000);

	return 0;
}