qt : day 3

1.完成登录框的按钮操作，并在登录成功后进行界面跳转

------------------------------------------------------------------
.pro
------------------------------------------------------------------
QT       += core gui  texttospeech
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
CONFIG += c++11
# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
SOURCES += \failed.cpp \main.cpp \success.cpp \widget.cppHEADERS += \failed.h \success.h \widget.h
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target
FORMS += \failed.ui \success.ui
------------------------------------------------------------------
widget.h
------------------------------------------------------------------
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QIcon>
#include <QLabel>
#include <QPushButton>
#include <QLineEdit>
#include <QTextToSpeech>
class Widget : public QWidget
{Q_OBJECT
public:Widget(QWidget *parent = nullptr);~Widget();private slots:void loginslot();void cancelslot();
signals:void failed_signal();void success_signal();
private:QPushButton *login_btn;QPushButton *cancel_btn;QLineEdit *account_edit;QLineEdit *pwd_edit;QLabel *main_lab;QLabel *account_lab;QLabel *pwd_lab;//创建一个播报员QTextToSpeech *speecher = new QTextToSpeech(this);
};
#endif // WIDGET_H
------------------------------------------------------------------
failed.h
------------------------------------------------------------------
#ifndef FAILED_H
#define FAILED_H
#include <QWidget>
#include <QIcon>
#include <QLabel>
namespace Ui {
class failed;
}
class failed : public QWidget
{Q_OBJECT
public slots:void fail_show();
public:explicit failed(QWidget *parent = nullptr);~failed();
private:Ui::failed *ui;
};
#endif // FAILED_H
------------------------------------------------------------------
success.h
------------------------------------------------------------------
#ifndef SUCCESS_H
#define SUCCESS_H
#include <QWidget>
#include <QIcon>
#include <QLabel>
namespace Ui {
class success;
}
class success : public QWidget
{Q_OBJECTpublic slots:void success_show();
public:explicit success(QWidget *parent = nullptr);~success();
private:Ui::success *ui;
};
#endif // SUCCESS_H
------------------------------------------------------------------
main.cpp
------------------------------------------------------------------
#include "widget.h"
#include "failed.h"
#include "success.h"
#include <QApplication>
int main(int argc, char *argv[])
{QApplication a(argc, argv);Widget w;failed f;success s;QObject::connect(&w,&Widget::failed_signal,&f,&failed::fail_show);QObject::connect(&w,&Widget::success_signal,&s,&success::success_show);w.show();return a.exec();
}
------------------------------------------------------------------
widget.cpp
------------------------------------------------------------------
#include "widget.h"
Widget::Widget(QWidget *parent): QWidget(parent)
{//---------------------------------窗口设置---------------------------------//设置窗口为固定大小this->setFixedSize(540,410);//设置窗口iconthis->setWindowIcon(QIcon("D:/B.work/6qt/day1/icon/wodepeizhenshi.png"));//设置窗口名this->setWindowTitle("鹏哥快聊");//---------------------------------标签设置---------------------------------//=====创建界面标签=====main_lab = new QLabel(this);//修改标签大小main_lab->resize(540,200);//在标签中插入图片main_lab->setPixmap(QPixmap("D:/B.work/6qt/day1/icon/logo.png"));//设置为自适应main_lab->setScaledContents(1);//=====创建账号标签=====account_lab = new QLabel(this);//修改标签大小account_lab->resize(50,40);//在标签中插入图片account_lab->setPixmap(QPixmap("D:/B.work/6qt/day1/icon/userName.jpg"));//移动到合适位置account_lab->move(90,220);//设置为自适应account_lab->setScaledContents(1);//=====创建密码标签=====pwd_lab = new QLabel(this);//修改标签大小pwd_lab->resize(account_lab->size());//在标签中插入图片pwd_lab->setPixmap(QPixmap("D:/B.work/6qt/day1/icon/passwd.jpg"));//移动到合适位置pwd_lab->move(account_lab->x(),account_lab->y()+80);//设置为自适应pwd_lab->setScaledContents(1);//---------------------------------按钮设置---------------------------------//=====创建登录按钮=====login_btn = new QPushButton(this);//设置按钮大小login_btn->resize(100,40);//在按钮上插入图片login_btn->setIcon(QIcon("D:/B.work/6qt/day1/icon/login.png"));//在按钮上输入文本login_btn->setText("登录");//移动到合适位置login_btn->move(270,360);connect(login_btn,&QPushButton::clicked,this,&Widget::loginslot);//=====创建取消按钮=====cancel_btn = new QPushButton(this);//设置按钮大小cancel_btn->resize(100,40);//在按钮上插入图片cancel_btn->setIcon(QIcon("D:/B.work/6qt/day1/icon/cancel.png"));//在按钮上输入文本cancel_btn->setText("取消");//移动到合适位置cancel_btn->move(login_btn->x()+120,login_btn->y());connect(cancel_btn,&QPushButton::clicked,this,&Widget::cancelslot);//---------------------------------输入设置---------------------------------//=====创建账号输入=====account_edit = new QLineEdit(this);//设置占位文本account_edit->setPlaceholderText("QQ号码/手机/邮箱");//设置大小account_edit->resize(200,40);//移动到适合位置account_edit->move(account_lab->x()+100,account_lab->y());//=====创建密码输入=====pwd_edit = new QLineEdit(this);//设置占位文本pwd_edit->setPlaceholderText("密码");//设置大小pwd_edit->resize(account_edit->size());//移动到合适位置pwd_edit->move(pwd_lab->x()+100,pwd_lab->y());//设置回文显示模式pwd_edit->setEchoMode(QLineEdit::Password);
}
Widget::~Widget()
{
}
void Widget::loginslot()
{//登录成功if(account_edit->text()=="admin"){if(pwd_edit->text()=="123456"){emit success_signal();speecher->say("登录成功");this->close();return ;}}//登录失败emit failed_signal();speecher->say("登录失败");pwd_edit->clear();
}
void Widget::cancelslot()
{this->close();
}
------------------------------------------------------------------
fail.cpp
------------------------------------------------------------------
#include "failed.h"
#include "ui_failed.h"
failed::failed(QWidget *parent) :QWidget(parent),ui(new Ui::failed)
{ui->setupUi(this);this->resize(100,70);this->setWindowIcon(QIcon("D:/B.work/6qt/day1/icon/cancel.png"));QLabel *fail_lab = new QLabel(this);fail_lab->setText("登陆失败");fail_lab->resize(100,50);fail_lab->move(0,10);
}
failed::~failed()
{delete ui;
}
void failed::fail_show()
{this->show();
}
------------------------------------------------------------------
success.cpp
------------------------------------------------------------------
#include "success.h"
#include "ui_success.h"
success::success(QWidget *parent) :QWidget(parent),ui(new Ui::success)
{ui->setupUi(this);QLabel *success_lab = new QLabel("登录成功",this);this->setWindowIcon(QIcon("D:/B.work/6qt/day1/icon/login.png"));this->resize(100,70);success_lab->resize(100,50);success_lab->move(0,10);
}
success::~success()
{delete ui;
}
void success::success_show()
{this->show();
}

2.模拟面试答案

1).多态，虚函数，纯虚函数概念
多态:一个名字的多种用途
静态多态:函数的重载(同一作用域下，定义函数名相同参数列表不同的函数)/运算符的重载(给定大多数运算符特殊的意义作用于类对象，使得代码书写更加简洁)
在编译时已经实现对多态的实现
动态多态:需要借助继承和虚函数完成。
虚函数:父类与子类为继承关系，发生在父子类之间，由父类提供虚函数，子类对父类中的虚函数进行重写操作，父类指针指向子类对象，并调用子类中重写父类的虚函数
纯虚函数:对于某些类中的函数，在该类没有实现的意义与必要，称为抽象类，需要子类对该函数进行重写，就可以把该类定义为纯虚函数
2).将"引用"作为函数参数有哪些特点
函数参数作用:解决函数数据没有交集问题，实现函数直接数据的交流
函数参数传递方式:直接将数据传递给目标函数(不会改变函数外的值)，地址传递(修改内存内的值，形参实参一起改变)，都需要占用内存空间
引用作为函数参数传递方式:传递值本身(本质还是地址传递，不需要新的容器接收数据，效率高)
3).结构体与联合体的区别
相同点:都属于构造数据类型，由相同或不同数据类型所组成的构造数据类型
不同点:所占内存空间的计算方式不同
结构体:各个成员所占内存空间之和，且遵循字节对齐原则
联合体:所有成员共享同一块内存空间，大小以最大的成员为主，使用时，任何成员都可以访问这片空间，但是访问大小不一样