Text Parser c++ code - c++

Question

I need a C++ code for the following problem:
i have a text file that i want to start reading from a specific line, then i need to print the output located between the characters --- <\s>
example: hello<\s>
i want the output to be hello
I think i should use text parser but not sure how!
#include <iostream>
#include <cstdlib>
#include <cctype>
#include <cstring>
#include <fstream>
#include <string>
using namespace std;
int main(int argc, char* argv[])
{
std::string line_;
ifstream file_("tty.txt");
if (file_.is_open())
{
while (getline(file_, line_))
{
std::cout << line_ << '\n';
}
file_.close();
}
else
std::cout << "error" << '\n';
std::cin.get();
system("PAUSE");
return 0;
}

Answer 1

You can load all text in one variable, and then with regex search all occurences of your desired pattern (in your case <sth>(any_aplha_numeric_character)*</sth> where * means one or more occurence, you can read about it at any std::regex tutorial)
Example:
std::smatch m;
std::string text = "<a>adsd</a> <a>esd</a>";
std::string::const_iterator searchStart(text.cbegin());
std::regex rgx("<a>[A-Za-z0-9\\s]*</a>");
while (std::regex_search(searchStart, text.cend(), m, rgx))
{
cout << m[0] << endl;
searchStart += m.position() + m.length();
}
gives: <a>adsd</a> and <a>esd</a> as a result, from which is very easy to extract that inner string