C++ read big file line by line and parse it.

#include <iostream>
#include <typeinfo>
#include <istream>
#include <fstream> 
#include <string>
#include <sstream>
#include <vector>
void readBigFileDemo7()
{
    string fullFileName = "D:\BigFileDemoRelease\logFile.txt";
    ifstream readFile(fullFileName);
    unsigned long long num = 0;
    string lineContent;
    try
    {
        while (std::getline(readFile, lineContent))
        {
            ++num;
            //Extract unsigned long long num from string 
            if (!lineContent.empty())
            {
                unsigned long long uul = stoull(lineContent);
                if (uul % 1000000 == 0)
                {
                    cout << lineContent << endl;
                }
            } 
        }
    }
    catch (exception ex)
    {
        cout << num << endl;
    }
}



int main()
{
    readBigFileDemo7();
    system("pause");
}