本次的程式目的是編寫一個登陸介面程式，包含了賬號密碼確認的功能，輸入框設定提示字元，密碼框採用password模式，設定登入按鈕為預設焦點。基本邏輯為：當輸入賬戶密碼時，按回車鍵或者點選登入按鈕，程式判斷賬號密碼是否正確，若正確則彈出主視窗，否則彈出警告框。程式效果如圖：

標頭檔案：

#ifndef LOGINDIALOG_H
#define LOGINDIALOG_H

#include <QDialog>
#include<QMessageBox>

namespace Ui {
class LoginDialog;
}

class LoginDialog : public QDialog
{
    Q_OBJECT

public:
    explicit LoginDialog(QWidget *parent = 0);
    ~LoginDialog();

private slots:
    void on_enter_pushButton_clicked();

private:
    Ui::LoginDialog *ui;
};

#endif // LOGINDIALOG_H
 

cpp檔案

#include "LoginDialog.h"
#include "ui_LoginDialog.h"

LoginDialog::LoginDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::LoginDialog)
{
    ui->setupUi(this);
    ui->enter_pushButton->setDefault(true);
    connect(ui->enter_pushButton,&QPushButton::clicked,this,&LoginDialog::on_enter_pushButton_clicked);
    connect(ui->quit_pushButton,&QPushButton::clicked,this,&LoginDialog::close);
}

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

void LoginDialog::on_enter_pushButton_clicked()
{
    if(ui->user_lineEdit->text() == tr("wangcong") && ui->password_lineEdit->text() == tr("lovefzj"))
    {
        accept();
    }
    else
    {
        QMessageBox::warning(this,tr("警告"),tr("使用者名稱或密碼錯誤"));
        ui->user_lineEdit->clear();
        ui->password_lineEdit->clear();
        ui->user_lineEdit->setFocus();
    }
}
 

#include "mainwindow.h"
#include"LoginDialog.h"
#include <QApplication>
#include<QDebug>
#include<QString>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    LoginDialog enterWindow;
    if(enterWindow.exec() == QDialog::Accepted)
    {
        w.show();
        return a.exec();
    }
    else
        return 0;
}