Qt "Form Load" function - c++

Question

i created new form in Qt and i would like to ask you where is form load function, where i can put my code.
And another problems are that file_exists doesn't work and i dont know why (i would like to use C native functions), and my Messagebox show before form load why? I would like to load while form and then show my Messagebox. And the last thing is that this->close(); at if statement doesn't work.
This is my code:
#include "nacitanie_okno.h"
#include "ui_nacitanie_okno.h"
#include "funkcie.h"
#include <iostream>
const char *subory[] = { "test.txt" } ;
nacitanie_okno::nacitanie_okno(QWidget *parent) :
QDialog(parent),
ui(new Ui::nacitanie_okno)
{
ui->setupUi(this);
int i;
int pocet = 1;
int percent = 20 / pocet;
for(i = 0; i < pocet ; i++){
if(file_exists(subory[i])){
ui->progressBar->setValue(ui->progressBar->value() + percent);
} else {
MessageBox("Hi","teeest"); // my own function for messagebox
this->close();
}
}
}
nacitanie_okno::~nacitanie_okno()
{
delete ui;
}
and in funkcie.h is this:
bool file_exists(const char * subor)
{
if (FILE * sub = fopen(subor, "r"))
{
fclose(sub);
return true;
}
return false;
}
thank you

Answer 1

The best way to create Form is pointers .
The "Load Form" function is the constructor of the class .
So when you want to create a form ,lets say you have "class Myform;" which is a gui form class, should be like this :
Myform* form = new Myform("constructor variables");
This will call the constructor where there you should write what you want as Form Load Function .
use this->hide this should work .
Print errno value , as fopen sets the errno value upon error .