test-hz-1/mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include "ui_mainwindow.h"
#include <QMainWindow>
#include <QPushButton>
#include <QList>
#include <qrandom.h>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr) : QMainWindow(parent) , ui(new Ui::MainWindow) { ui->setupUi(this); }
    ~MainWindow() { delete ui; }

private:
    QPushButton * button_1 = new QPushButton("TestButton");
    QList <QPushButton *> * list = new QList <QPushButton *>();

    void remove_(){
        while (ui->vl->itemAt(0)){
            ui->vl->removeItem(ui->vl->itemAt(0));
        }
    }

    void make_(){
        QStringList texts = {"a", "b", "c"};
        foreach (QString text, texts){
            QPushButton *button = new QPushButton(text);
            bg_gen(button);
            ui->vl->addWidget(button);
        }
    }

    void bg_gen(QWidget * wg){
        QString r,g,b;
        r.setNum(QRandomGenerator::global()->bounded(1,255));
        g.setNum(QRandomGenerator::global()->bounded(1,255));
        b.setNum(QRandomGenerator::global()->bounded(1,255));
        wg->setStyleSheet("background: rgb(" + r + "," + g + "," + b + ");");
    }
private slots:
    void on_add_3_clicked(){make_();}
    void on_del_all_clicked(){remove_();}

    void on_del_1_clicked() { ui->vl->removeWidget(button_1);}
    void on_add_1_clicked(){ ui->vl->addWidget(button_1); }

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H