How to insert c++ find into a while loop? - c++

Question

I use a while loop with the find function in c++ but I need to use the position found like the condition of the while loop but Visual Studio shome me
An unhandled exception of type 'System.Runtime.InteropServices.SEHException' occured in Test.exe
Additional information: External component has thrown an exception.
I use this code:
int dim=myString.length();
while (dim>=0)
{
size_t pos1 = myString.find("<article");
size_t pos2 = myString.find("</article>");
std::string buf = myString.substr(pos1, pos2 - pos1 + 10);
myString = myString.substr(pos2 + 10);
ofstream myfile("body.txt");
if (myfile.is_open())
{
myfile << myString;
myfile.close();
}
else cout << "Unable to open file";
//cout << myString << endl;
ptree xmlTree;
string title[1000];
int j = 0;
try
{
stringstream ss;
ss << buf;
read_xml(ss, xmlTree);
const ptree & formats = xmlTree.get_child("article", empty_ptree());
BOOST_FOREACH(const ptree::value_type & f, formats)
{
string at = f.first + ATTR_SET;
const ptree & attributes = f.second.get_child("<xmlattr>", empty_ptree());
//cout << "Extracting attributes from " << at << ":" << endl;
BOOST_FOREACH(const ptree::value_type &v, attributes)
{
string first = v.first.data();
//cout << "First: " << v.first.data() << " Second: " << v.second.data() << endl;
if (first == "title")
{
title[j] = v.second.data();
j++;
}
}
}
for (int a = 0; a < j; a++)
{
cout << title[a] << endl;
}
}
catch (xml_parser_error &e) {
cout << "Failed to read config xml " << e.what() << endl;
}
catch (...) {
cout << "Failed to read config xml with unknown error" << endl;
}
dim = dim - pos2;
}
what is the problem?

Answer 1

I resolve my problem thanks to the help of PaulMcKenzie. I modify my code to insert a boolean variable and to control if pos1 and pos2 find the correct string which are <article and </article>.
This is the code:
int dim = myString.length();
boolean in=true;
while (in==true)
{
size_t pos1 = myString.find("<article");
size_t pos2 = myString.find("</article>");
if (pos1 != std::string::npos && pos2 != std::string::npos)
{
std::string buf = myString.substr(pos1, pos2 - pos1 + 10);
myString = myString.substr(pos2 + 10);
ofstream myfile("body.txt");
if (myfile.is_open())
{
myfile << myString;
myfile.close();
}
else cout << "Unable to open file";
//some code
dim = dim - myString.length();
in = true;
}
else
{
in = false;
cout << " - - - - - - - - - - " << endl;
}
}