C++ runtime Error in Running Program

[ramin.lich]

hi all
this is Full Source of My Program

#include "mainwindow.h"
#include <QApplication>
#include <QSystemTrayIcon>
#include <QMenu>
#include <QAction>
#include <QFileDialog>
#include <QMessageBox>
#include <thread>
#include <fstream>
#include <QTextStream>
#include <time.h>
#include <windows.h>
using namespace std;
 
 
 
    const tm* timeinfos;
void tray();
void refresh();
void starts();
void wait();
ofstream dif("d:\\dif.txt");
const char* const path = "d:\\dif.txt" ;
void starts();
int hour=0,minu=0;
ofstream times("d:\\time.txt");
struct tm * timeinfo;
 time_t rawtime = time(0) ;
 int sec,secd;
    MainWindow w;
 
 
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    w.hide();
    std::thread first(tray);
    std::thread second(starts);
    std::thread third(refresh);
    starts();
            first.join();
            third.join();
 
    return a.exec();
}
 
 
void tray(){
    QSystemTrayIcon *trayIcon=new QSystemTrayIcon();
       QMenu *menu=new QMenu("TimeUsage");
       menu->addAction("Open");
       menu->addAction("Exit");
       trayIcon->setContextMenu(menu);
       trayIcon->setIcon(QIcon("e:\\icon.png"));
       trayIcon->show();
       trayIcon->showMessage("TimeUsage","TimeUsage Is Here!");
 
       QObject::connect(menu,&QMenu::triggered,[&w](QAction* act){
 
           const auto& text = act->text();
           if(text=="Exit"){
               QApplication::exit();
           }
           else if(text=="Open"){
               w.show();
           }
 
 
       });
}
 
 
void refresh(){
    for(;;){
        wait();
    time_t now = time(0) ;
        ifstream dif(path);
        time_t earlier = 0  ;
        dif >> earlier ;
 
        double secs = difftime( now, earlier );
        minu=secs/60;
        while(minu>60){
            minu-=60;
            hour++;
        }
        QFile times("d:\\time.txt");
        times.open(QIODevice::Append);
        QTextStream stream(&times);
        stream<<asctime(timeinfos)<<endl<<hour<<"/"<<minu<<endl;
    }
}
 
 
void starts(){
    timeinfos = localtime ( &rawtime );
 
    ofstream dif(path);
    dif << rawtime << '\n' ;
    dif.close();
    refresh();
}
 
 
void wait(){
    int i;
    for (i=0; i<=10; ++i) {
          this_thread::sleep_for (chrono::seconds(1));
}
}

#include "mainwindow.h"
#include <QApplication>
#include <QSystemTrayIcon>
#include <QMenu>
#include <QAction>
#include <QFileDialog>
#include <QMessageBox>
#include <thread>
#include <fstream>
#include <QTextStream>
#include <time.h>
#include <windows.h>
using namespace std;



    const tm* timeinfos;
void tray();
void refresh();
void starts();
void wait();
ofstream dif("d:\\dif.txt");
const char* const path = "d:\\dif.txt" ;
void starts();
int hour=0,minu=0;
ofstream times("d:\\time.txt");
struct tm * timeinfo;
 time_t rawtime = time(0) ;
 int sec,secd;
    MainWindow w;



int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    w.hide();
    std::thread first(tray);
    std::thread second(starts);
    std::thread third(refresh);
    starts();
            first.join();
            third.join();

    return a.exec();
}


void tray(){
    QSystemTrayIcon *trayIcon=new QSystemTrayIcon();
       QMenu *menu=new QMenu("TimeUsage");
       menu->addAction("Open");
       menu->addAction("Exit");
       trayIcon->setContextMenu(menu);
       trayIcon->setIcon(QIcon("e:\\icon.png"));
       trayIcon->show();
       trayIcon->showMessage("TimeUsage","TimeUsage Is Here!");

       QObject::connect(menu,&QMenu::triggered,[&w](QAction* act){

           const auto& text = act->text();
           if(text=="Exit"){
               QApplication::exit();
           }
           else if(text=="Open"){
               w.show();
           }


       });
}


void refresh(){
    for(;;){
        wait();
    time_t now = time(0) ;
        ifstream dif(path);
        time_t earlier = 0  ;
        dif >> earlier ;

        double secs = difftime( now, earlier );
        minu=secs/60;
        while(minu>60){
            minu-=60;
            hour++;
        }
        QFile times("d:\\time.txt");
        times.open(QIODevice::Append);
        QTextStream stream(&times);
        stream<<asctime(timeinfos)<<endl<<hour<<"/"<<minu<<endl;
    }
}


void starts(){
    timeinfos = localtime ( &rawtime );

    ofstream dif(path);
    dif << rawtime << '\n' ;
    dif.close();
    refresh();
}


void wait(){
    int i;
    for (i=0; i<=10; ++i) {
          this_thread::sleep_for (chrono::seconds(1));
}
}

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the Program Has No Problem With Compiling But will Not Run And I Get the Following Error:
Untitled.png
Any Help Will Be Great

[faldzip]

1. You have to create QApplication before creating any widgets - if you must have this global variable MainWindow w; then make it a pointer and then allocate on a heap after QApplication creation.
2. But it is not going to work either as you cannot access the widgets from threads other than UI thread (which is the main thread).

[rezas1000]

this code is completely wrong. So what is the difference between Library of the console and The library of the desktop?