rapidxml parsing misbehavior when subfunction is used - c++

Question

everyone! I am using rapidxml to parse my setting file. When I do everything in a single function, it works well. But when I try to add some functions to do the work, it always give std::exception. Does anyone know the reason?
A simple code example is
#include <stdexcept>
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include "rapidxml.hpp"
struct MyConfig{
bool LES_FLAG, ITP_FLAG;
int calcCase, dataInterval, maxIter;
double va, lesCoef, eigenLength, Re;
double xLow, xUp, yLow, yUp, maxTime;
}config;
void readConfig(const char* fileName);
void parseFlag(rapidxml::xml_node<> *node, char *flagName, bool &flag, int namesize=0);
void parseFloat(rapidxml::xml_node<> *node, char *name, double &variable, int namesize=0);
void parseInt(rapidxml::xml_node<> *node, char *name, int &variable, int namesize=0);
void parseString(rapidxml::xml_node<> *node, char *name, std::string &str, int namesize=0);
int main(int argn, char** argv){
try{
readConfig("test.xml");
}
catch (std::exception e)
{
std::cout << e.what() << std::endl;
}
}
void readConfig(const char* fileName){
std::ifstream myfile(fileName);
if (!myfile.is_open())
throw std::runtime_error("Can not open the configuration file!\n");
std::stringstream buffer;
buffer << myfile.rdbuf();
myfile.close();
try{
rapidxml::xml_document<> doc;
doc.parse<0>(&buffer.str()[0]);
rapidxml::xml_node<> *rNode = doc.first_node("Config_2DVPM");
rapidxml::xml_node<> *cnode = rNode->first_node("flags",5,false);
parseFlag(cnode, "LES_FLAG", config.LES_FLAG);
parseFlag(cnode, "ITP_FLAG", config.ITP_FLAG);
cnode = rNode->first_node("float",5,false);
cnode = rNode->first_node("float",5,false);
parseFloat(cnode, "va", config.va, 2);
parseFloat(cnode, "lesCoef", config.lesCoef, 7);
parseFloat(cnode, "eigenLength", config.eigenLength, 11);
parseFloat(cnode, "Re", config.Re, 2);
parseFloat(cnode, "xLow", config.xLow, 4);
parseFloat(cnode, "xUp", config.xUp, 3);
parseFloat(cnode, "yLow", config.yLow, 4);
parseFloat(cnode, "yUp", config.yUp, 3);
parseFloat(cnode, "maxTime", config.maxTime, 7);
cnode = rNode->first_node("int",3,false);
parseInt(cnode, "calcCase", config.calcCase);
parseInt(cnode, "dataInterval", config.dataInterval);
parseInt(cnode, "maxIter", config.maxIter);
}
catch (rapidxml::parse_error& e)
{
std::string ss = std::string("xml parse error: ") + e.what();
throw std::runtime_error(ss);
}
}
void parseFlag(rapidxml::xml_node<> *node, char* name, bool &flag, int namesize)
{
char *str = node->first_attribute(name, namesize, false)->value();
if (str == NULL)
{
std::string ss = std::string("Undefined attribute in flags: ") + name;
throw std::runtime_error(ss);
}
if (strcmp(str, "1") == 0 || strcmp(str, "true") == 0 || strcmp(str, "True") == 0)
flag = true;
else flag = false;
}
void parseFloat(rapidxml::xml_node<> *node, char* name,
double &variable, int namesize)
{
char* str = node->first_attribute(name, namesize, false)->value();
if (*str == '\0')
{
std::string ss = std::string("Undefined attribute in float: ") + name;
throw std::runtime_error(ss);
}
std::stringstream ss(str);
ss >> variable;
}
void parseInt(rapidxml::xml_node<> *node, char* name,
int &variable, int namesize)
{
char *str = node->first_attribute(name, namesize, false)->value();
if (*str == '\0')
{
std::string ss = std::string("Undefined attribute in int: ") + name;
throw std::runtime_error(ss);
}
std::stringstream ss(str);
ss >> variable;
}
void Calculation::parseString(rapidxml::xml_node<> *node, char* name,
std::string &res, int namesize)
{
char *str = node->first_attribute(name, namesize, false)->value();
if (*str == '\0')
{
std::string ss = std::string("Undefined attribute in int: ") + name;
throw std::runtime_error(ss);
}
res = str;
}
The example file text.xml is
<?xml version="1.0" encoding="UTF-8"?>
<Config_2DVPM version="1.0">
<flags LES_FLAG="true" ITP_FLAG="false"/>
<float va="1.0" lesCoef="0.15" eigenLength="1.0" Re="500" maxTime="15"
xLow="-1" xUp="5" yLow="-1" yUp="1"/>
<int calcCase="0" dataInterval="200" maxIter="100000"/>
<string test="haha"/>
</Config_2DVPM>
The code always gives an output std::exception. After some check, the problem always happens when I parse the attribute "eingenLength".