C++ QT5 运行时错误read access violation at: 0x0, flags=0x0 (first chance)

[gouckchenwy]

//logindlg.h
#ifndef SIGNINDLG_H
#define SIGNINDLG_H

#include <QDialog>
#include<QMessageBox>
#include<QString>
#include<QPushButton>
#include"ui_signindlg.h"

using namespace std;

namespace Ui {
class SignInDlg;
}

class SignInDlg : public QDialog, public Ui::SignInDlg
{

    Q_OBJECT

public:

    explicit SignInDlg(QWidget *parent = 0);

    ~SignInDlg();

    void check();

private:

    Ui::SignInDlg *ui;
};

#endif // SIGNINDLG_H

//logindlg.cpp
#include "signindlg.h"
#include "ui_signindlg.h"

SignInDlg::SignInDlg(QWidget *parent) :

    QDialog(parent),

    ui(new Ui::SignInDlg)
{

    ui->setupUi(this);
   
 //此处发生错误
    QObject::connect(pushButton, &QPushButton::clicked, this, &SignInDlg::check);  

    check();
}

void SignInDlg::check()
{

    QString username;

    QString password;

    username = ui->usernameLineEdit->text();

    if (username.length() > 16)

    {

        QMessageBox msgBox;

        msgBox.setText("Username cannot be longer than 16 chars!");

        msgBox.setStandardButtons(QMessageBox::Yes);

        msgBox.setDefaultButton(QMessageBox::Yes);

    }
}

SignInDlg::~SignInDlg()
{

    delete ui;
}

异常被触发：
底层停止了因为它触发了一个异常。

在线程0中停止，因为: Exception at 0x6d9a937a, code: 0xc0000005: read access violation at: 0x0, flags=0x0。

[火头军]

指针访问越界，你的pushbutton 哪里来的