call on Qt widget from another

#include "bioinfo.h"
#include "ui_bioinfo.h"
#include "biodisplay.h"
#include <iostream>

using namespace std;

BioInfo::BioInfo(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::BioInfo)
{
    ui->setupUi(this);
}

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

void BioInfo::on_buttonBox_clicked(QAbstractButton *button)
{
    string name = ui->nameLineEdit->text().toStdString();
    string age = ui->ageLineEdit->text().toStdString();

    cout << "your name is:  " << name << endl;
    cout << "your age is:  " << age << endl;

    //call on the bioDisplay widget to show user's name and age
    bioDisplay *dialog = new bioDisplay();
   /*
    the Qlabel object name that will diplay the name is called nameLabel and the
    one that will display age is called ageLabel
    i've tried ageLabel->setText(age) and nameLabel->setText(name), but my ide says
    error: ‘ageDisplay’ was not declared in this scope

    */
    dialog->setWindowTitle("Dialog");
    ageDisplay->text();
    dialog->show();



}