Hungarian PlateNumber Generator v1 Cplusplus

#include "platenumb.h"
#include "./ui_platenumb.h"
#include <unordered_set>

PlateNumb::PlateNumb(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::PlateNumb)
{
    ui->setupUi(this);
    ui->GenPlateBT1->setVisible(false);

}

PlateNumb::~PlateNumb()
{
    delete ui;
}

std::unordered_set <QString> setPlate;

QString genPlate ="";

void PlateNumb::on_GenPlateBT1_clicked()
{



    QString albet;
    char al2;
    genPlate="";
    for (int ch = 'A'; ch <= 'Z'; ch++) {
        al2=(char)ch;
        albet+=al2;
    }



    for (int i=0;i<4;i++){
        int randTemp = rand() % albet.length();

        genPlate.append(albet[randTemp]);
    }

    genPlate.append("-") ;
    for (int i=0;i<3;i++){

        int randTemp = rand() % 10;
        genPlate.append(QString::number(randTemp));

}
    setPlate.insert(genPlate);


}

void PlateNumb::on_GenLotBT2_clicked()
{
  for (int i =0; i<100;i++){
        PlateNumb::on_GenPlateBT1_clicked();
  }
  for (auto i = setPlate.begin();i!=setPlate.end();i++)
  {
        ui->GennedPlateListLE1->append(*i);

  }

}