How to declare a global variable which calls an object in C++? - c++

Question

mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
audioRecorder = new QAudioRecorder;
QAudioEncoderSettings audioSettings;
audioSettings.setCodec("audio/amr");
audioSettings.setQuality(QMultimedia::HighQuality);
audioRecorder->setEncodingSettings(audioSettings);
audioRecorder->setOutputLocation(QUrl::fromLocalFile("test.amr"));
audioRecorder->record();
}
void MainWindow::on_pushButton_2_clicked()
{
//How to use audioRecorder variable???
}
I want to use the audioRecorder variable into the last method of my code. because when I declare audioRecorder = new QAudioRecorder;, the variable audio recorder is only accessible into the method on_pushButton_clicked(), so I want to make this variable usable into the method n_pushButton_2_clicked(). How to do it ?

Answer 1

Like some person said in the comments, you need to have your QAudioRecorder object declared as a member of your MainWindow class.
So basically you need something like this :
QAudioRecorder* audioRecorder;//This could also be a shared_ptr
Then, your audioRecorder object is created in your on_pushButton_clicked() function.
You can now use it in on_pushButton_2_clicked() function.
However, this is quite unsafe, for example, if you did not create the audioRecorder before calling on_pushButton_2_clicked(), audioRecorder is not going to point to a valid object and this will most certainly crash your project.
So before using it in on_pushButton_2_clicked(), verify if its valid:
if(audioRecorder)
{
// You can use audioRecorder safely here
}