C++ QT开发 学习笔记(1)

C++ QT开发 学习笔记(1)

考试系统

创建项目

新建Qt桌面应用程序，项目名：ExamSys。

类信息：类名LoginDialog继承自QDialog

（1） ExamSys.pro

工程文件，包含当前工程的相关信息。

QDialog 是 Qt 框架中用于创建对话框的基类。对话框是一种特殊类型的窗口，通常用于短期的交互和信息交换，比如用户输入、设置选项、文件选择等。QDialog 提供了许多专为这种用途设计的特性和功能。

ExamSys.pro

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = ExamSys
TEMPLATE = app

logindialog.h

#ifndef LOGINDIALOG_H
#define LOGINDIALOG_H

#include <QDialog>

namespace Ui {
   
class LoginDialog; //Ui_LoginDialog son class, use for describe the login window detail message.
}

class LoginDialog : public QDialog
{
   
    Q_OBJECT  //Support signal and slots

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

private:
    Ui::LoginDialog *ui;
};

#endif // LOGINDIALOG_H

logindialog.cpp

#include "logindialog.h"
#include "ui_logindialog.h"

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

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

main.cpp

#include "logindialog.h"
#include <QApplication>
#include <examdialog.h>

int main(int argc, char *argv[])
{
   
    QApplication a(argc, argv); //Define the apps object
    LoginDialog w;				//Define the window object
    w.show();					//Display window
    return a.exec();			//Enter APP execeute loop
}

logindialog.ui

登录窗口界面文件。

登录界面

设计模式下添加账号、密码标签，账号、密码输入框，登录、取消按钮，并修改对象名，添加资源文件imgage.qrc,给imgLabel添加图片资源做背景。

logindialog.cpp构造函数中设置窗体标题、风格

LoginDialog::LoginDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::LoginDialog)
{
   
    ui->setupUi(this);
    this->resize(600,400);
    setFixedSize(width(),height());
    this->setWindowTitle("Cat Exam");
    this->setWindowFlags(Qt::Dialog| Qt::WindowCloseButtonHint);
    this->setWindowFlags(Qt::Window| Qt::WindowFullscreenButtonHint);
}

验证邮箱地址

给登录按钮添加响应点击信号的槽方法:

设计模式下,右键单击登录按钮，选择“转到槽”，选择点击信号clicked().

给槽方法void LoginDialog::on_loginBtn_clicked()添加如下代码：

void LoginDialog::on_login_Button_clicked()
{
   
    //QMessageBox::information(this,"Hint","Slot method used");
    //Verify the email address username@address   ex:123980@qq.com
    //Symbol decalration: ^string start  &string end
    //+match times>=1 *match any times(include 0 times)  {n,m}match times at least n times, at most m times.
    QRegExp rx("^[A-Za-z0-9]+([_\.][A-Za-z0-9]+)*@([A-Za-z0-9\-]+\.)+[A-Za-z0-9]{2,6}$");

    bool res = rx.exactMatch(ui->account_edit->text());
    if(!res)// If failed match
    {
   
        QMessageBox::information(this,"Hint","Invalid email address, please reenter the email address");
    }
    else
    {
   
        QMessageBox::information(this,"Hint","Welcome to the CAT exam!");
    }

注意:需要加上头文件 include <QMessageBox>

验证账号密码 (通过账号密码保存在文档的方式)

在logindialog.cpp添加头文件

#include <QFile>

#include <QTextStream>

这两个头文件的引入有特定的目的，主要涉及到文件处理和文本数据的流式读写

编辑 void LoginDialog::on_loginBtn_clicked()方法

void LoginDialog::on_login_Button_clicked()
{
   
    //QMessageBox::information(this,"Hint","Slot method used");
    //Verify the email address username@address   ex:123980@qq.com
    //Symbol decalration: ^string start  &string end
    //+match times>=1 *match any times(include 0 times)  {n,m}match times at least n times, at most m times.
    QRegExp rx("^[A-Za-z0-9]+([_\.][A-Za-z0-9]+)*@([A-Za-z0-9\-]+\.)+[A-Za-z0-9]{2,6}$");

    bool res = rx.exactMatch(ui->account_edit->text());
    if(!res)// If failed match
    {
   
        QMessageBox::information(this,"Hint","Invalid email address, please reenter the email address");
        ui->account_edit->clear();
        ui->code_edit->clear();
        ui->account_edit->setFocus();
        return;
    }

    else
    {
   
        //QMessageBox::information(this,"Hint","Welcome to the cat EXAM!");
        QString filename;       //Account & password data file
        QString strAccInput;    //User input account
        QString strCode;        //User input password
        QString strLine;        //Every line read data
        QStringList strList;    //Use for seperate the line from strLine for account and password

        filename = "../account.txt";    //According to the debug folder. so need to go previous folder get account.txt
        strAccInput = ui->account_edit->text();
        strCode = ui->code_edit->text();

        QFile file(filename);
        QTextStream stream(&file);
        if (file.open(QIODevice::ReadOnly | QIODevice::Text)