Hi, i'm making an currency converter app.
I go online, download a html and save it into a txt file, which i parse afterwards for the exchange rates.

.h
Qt Code: 
  1. #ifndef DOWNLOADER_H
  2. #define DOWNLOADER_H
  3.  
  4. #include <QObject>
  5. #include <QNetworkAccessManager>
  6. #include <QNetworkRequest>
  7. #include <QNetworkReply>
  8. #include <QUrl>
  9. #include <QFile>
  10. #include <QDebug>
  11. #include <QMessageBox>
  12. #include <string>
  13. #include <Windows.h>
  14. #include <qstring.h>
  15.  
  16.  
  17. class downloader : public QObject
  18. {
  19.     Q_OBJECT
  20. public:
  21.     explicit downloader(QObject *parent = 0);
  22.  
  23.     void Do_download();
  24.  
  25. public slots:
  26.     void replyFinished (QNetworkReply *reply);
  27.  
  28. private:
  29.     QNetworkAccessManager *manager;
  30.  
  31. };
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.cpp

Qt Code: 
  1. #include "downloader.h"
  2. #include "strings.h"
  3. #include <string>
  4. #include <Windows.h>
  5.  
  6. downloader::downloader(QObject *parent) :
  7.     QObject(parent)
  8. {
  9.  
  10. }
  11.  
  12.  
  13. void downloader::Do_download()
  14. {
  15.     manager = new QNetworkAccessManager(this);
  16.  
  17.     connect(manager, SIGNAL(finished(QNetworkReply*)),
  18.             this,SLOT(replyFinished(QNetworkReply*)));
  19.  
  20.             manager->get(QNetworkRequest(QUrl("http://www.hnb.hr/tecajn/hvazeca.htm")));
  21. }
  22.  
  23. void downloader::replyFinished(QNetworkReply *reply)
  24. {
  25.     if(reply->error())
  26.     {
  27.         QMessageBox msgBox;
  28. 		msgBox.setText(strings::msgBoxDownReplyError);
  29.         msgBox.exec();
  30.     }
  31.     else
  32.     {
  33.  
  34. 		QFile *file = new QFile("C:/Qt/test/downloaded.txt");
  35.         QByteArray data = reply->readAll();
  36.  
  37.         if(file->open(QIODevice::ReadWrite | QIODevice::Truncate | QIODevice::Text))
  38.             {
  39.             file->write(data);
  40.             file->flush();
  41.             file->close();
  42.         }
  43.         delete file;
  44.  
  45.     }
  46.     reply->deleteLater();
  47.  
  48. }
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parser.h

Qt Code: 
  1. #ifndef PARSER_H
  2. #define PARSER_H
  3.  
  4.  
  5. #include <QMessageBox>
  6. #include <QStringList>
  7. #include <string>
  8. #include <sstream>
  9. #include <stdlib.h>
  10. #include <fstream>
  11. #include <iostream>
  12. #include <algorithm>
  13. #include <string>
  14. #include <Windows.h>
  15.  
  16.  
  17. class parser 
  18.  
  19. {
  20.  
  21. public:
  22.      explicit parser();
  23.  
  24.     QStringList currency_list;
  25. 	std::list<std::string> curr_list;
  26.  
  27.     void process_line(std::string line, std::map<std::string,double> &my_map, std::string curr_string);
  28.     int read_line(std::map<std::string,double> &my_map);
  29.  
  30.     void init_list();
  31.  
  32. 	std::string getExePathParser();
  33.  
  34. private:
  35.  
  36. };
  37.  
  38. #endif // PARSER_H
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parser.cpp

Qt Code: 
  1. #include "parser.h"
  2. #include "calculator.h"
  3. #include "strings.h"
  4. #include <string>
  5.  
  6. parser::parser()   
  7. {
  8.         init_list();
  9.  
  10. }
  11. void parser::process_line(std::string line, std::map<std::string,double> &my_map, std::string curr_string)
  12. {
  13. 	double curr;
  14. 	std::string temp;
  15.  
  16. 	temp = line.substr(52,8);
  17.  
  18. 	std::replace(temp.begin(),temp.end(),',','.');
  19.  
  20. 	curr = std::stod(temp,NULL);
  21.  
  22. 	my_map.insert(std::make_pair(curr_string,curr));
  23.  
  24. }
  25.  
  26.  
  27. int parser::read_line(std::map<std::string,double> &my_map)
  28. {
  29.  
  30. 	std::list<std::string>::iterator iter;
  31. 	std::string linija;
  32. 	std::ifstream file_("C:/Qt/test/downloaded.txt");
  33.  
  34. 	if(file_.fail())
  35. 	{
  36. 		QMessageBox msgBox;
  37. 		msgBox.setText(strings::msgBoxOpeningError);
  38.         msgBox.exec();
  39. 	}
  40.  
  41. 	else if(file_.is_open())
  42. 	{
  43. 		while(std::getline(file_,linija))
  44. 		{
  45. 			for(iter=curr_list.begin(); iter != curr_list.end(); ++iter)
  46. 			{
  47. 			if(linija.find(*iter) != std::string::npos)
  48. 			process_line(linija, my_map, *iter);
  49. 			}
  50. 		}
  51. 		file_.close();
  52. 	}
  53.  
  54.     return 0;
  55. }
  56.  
  57.  
  58.  
  59. void parser::init_list()
  60. {
  61.     currency_list << "HRK" << "CAD" << "CZK" << "DKK" << "HUF" 
  62. 		          << "JPY" << "NOK" << "SEK" << "CHF" << "GBP" 
  63. 			      << "USD" << "EUR" << "PLN" << "AUD";
  64. 	curr_list.push_back("HRK");
  65. 	curr_list.push_back("CAD");
  66. 	curr_list.push_back("CZK");
  67. 	curr_list.push_back("DKK");
  68. 	curr_list.push_back("HUF");
  69. 	curr_list.push_back("JPY");
  70. 	curr_list.push_back("NOK");
  71. 	curr_list.push_back("SEK");
  72. 	curr_list.push_back("CHF");
  73. 	curr_list.push_back("GBP");
  74. 	curr_list.push_back("USD");
  75. 	curr_list.push_back("EUR");
  76. 	curr_list.push_back("PLN");
  77. 	curr_list.push_back("AUD");
  78.  
  79.  
  80. }
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and my main

Qt Code: 
  1. int main(int argc, char *argv[])
  2. {
  3.     QApplication a(argc, argv);
  4.  
  5. 	std::map<std::string,double> currency_map;
  6.  
  7.  
  8.     downloader d;
  9.     d.Do_download();
  10.  
  11.  
  12. 	parser p;
  13.     p.read_line(currency_map);
  14.  
  15.  
  16.     MainWindow w(currency_map);
  17.     w.show();
  18.  
  19.  
  20.     return a.exec();
  21. };
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It was working good, but then i changed the path for the .txt file i create.
And the first time i run the app, i get a msgBoxError from my parser class
Qt Code: 
  1. if(file_.fail())
  2. 	{
  3. 		QMessageBox msgBox;
  4. 		msgBox.setText(strings::msgBoxOpeningError);
  5.         msgBox.exec();
  6. 	}
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this part of code pops up.
then i shut it down. run the app again, and it's all working well.
so everytime i change the file path, the first running of the app wont work.
can someone help me out, and spot what's wrong here?

(i have to use basic c++ in some parts of the code, don't ask)