QT可视化程序设计基础第五章课后习题

最近看了这本和QT相关的书,下面是第五章的习题及我的理解

题目1:Qt的信号和槽函数分别指什么?

当信号发出的时候,信号绑定的槽函数会自动回调.

信号的本质应该是事件,然后槽函数的本质应该是成员函数,分布是Signal和SLOT

然后它有三种写法:

qt5.0之前

//     发送者    信号            接收者     槽函数      
connect(sender,SIGNAL(SIGNAL()),receiver,SLOT(handle()));

qt5.0之后

connect(sender,&sender::signal,receiver,&receiver::handle);//最后还有个type,一般默认

使用lambda表达式,c++11出来的新特性

connect(sender,&sender::signal::signal,[=](){信号触发之后的一些操作
});

题目2 输入十进制文本框中显示二进制,八进制,十六进制

思路:要将十进制变成其他进制并且显示到文本框中,考虑使用QString::number(int,几进制) 页面布局主要是定义一个输入框,三个输出框,一个确定按钮,一个清楚按钮,然后使用QLayout进行布局,使用它的addwidget函数放置上面的组件,最后setlayout.

源代码如下:

h文件

#ifndef TEST2_H
#define TEST2_H#include <QObject>
#include <QWidget>
#include <QLabel>
#include <QLineEdit>
#include <QPushButton>
class test2 : public QWidget //继承否则报错
{Q_OBJECT
public:test2();public://定义变量QLabel  * title;            //标题QLabel  * l_input;QLabel  * l_2;QLabel  * l_8;QLabel  * l_16;QLineEdit * m_Input;        //输入框QLineEdit * m_2;            //2进制QLineEdit * m_8;            //8进制QLineEdit * m_16;           //16进制QPushButton * btn_sure;     //确定按钮QPushButton * btn_clear;    //清除private slots:void on_btn_sure_clicked();void on_btn_clear_clicked();;};#endif // TEST2_H

c文件

#include "test2.h"#include <QGridLayout>
#include <QString>
#include <QString>
#include <QDebug>test2::test2()
{this->setFixedSize(300,180);    //变量初始化title = new QLabel("5单元习题2", this);l_input=new QLabel("输入框",this);l_2 = new QLabel("2进制",this);l_8 = new QLabel("8进制",this);l_16 = new QLabel("16进制",this);m_Input = new QLineEdit(this);m_2 = new QLineEdit(this);m_8 = new QLineEdit(this);m_16 = new QLineEdit(this);btn_sure = new QPushButton("确定", this);btn_clear = new QPushButton("清除", this);QGridLayout * Grid = new QGridLayout;Grid->addWidget(title,1,1,1,4,Qt::AlignHCenter); //标题Grid->addWidget(l_input,2,1,1,4,Qt::AlignLeft);Grid->addWidget(m_Input,2,2,1,4,Qt::Alignment());Grid->addWidget(l_2,3,1,1,4,Qt::AlignLeft); //标题Grid->addWidget(m_2,3,2,1,4,Qt::Alignment());   //2进制//m_2->setReadOnly(true);Grid->addWidget(l_8,4,1,1,4,Qt::AlignLeft); //标题Grid->addWidget(m_8,4,2,1,4,Qt::Alignment());   //8进制//m_8->setReadOnly(true);Grid->addWidget(l_16,5,1,1,4,Qt::AlignLeft); //标题Grid->addWidget(m_16,5,2,1,4,Qt::Alignment());  //16进制//m_16->setReadOnly(true);Grid->addWidget(btn_sure, 6, 1, 1, 2);      // 确定按钮Grid->addWidget(btn_clear, 6, 3, 1, 2);     // 清除按钮this->setLayout(Grid);// 连接信号与槽connect(btn_sure, SIGNAL(clicked(bool)), this, SLOT(on_btn_sure_clicked()));connect(btn_clear, SIGNAL(clicked(bool)), this, SLOT(on_btn_clear_clicked()));}void test2::on_btn_sure_clicked()
{qDebug()<<"xxx";//将输入的转换为intint input_content = m_Input->text().toInt();qDebug()<<input_content;QString n_2 = QString::number(input_content,2);//2进制QString n_8 = QString::number(input_content,8);//8进制QString n_16 = QString::number(input_content,16);//16进制m_2->setText(n_2);m_8->setText(n_8);m_16->setText(n_16);}void test2::on_btn_clear_clicked()
{m_2->clear();m_8->clear();m_16->clear();
}

最后在main函数里面调用,show出来就行了.

题目三通过实现两个对话框互相发送消息的功能来熟悉Qt的信号和槽.具体功能:程序为单对话框程序,单击打开按钮可以再次打开一个对话框.两个对话框都有发送消息按钮,输入消息文本框以及编辑消息文本框,并可实现互发消息的功能.

实现思路:首先是定义两个类,使用声明那些变量,然后使用layout完成界面布局,两边定义signal和slot,绑定按钮触发signal,使用emit关键字将信息传递出去

源码如下:

diag1:

#ifndef DIALOGCONNECT_H
#define DIALOGCONNECT_H#include "dialog2.h"#include <QDialog>
#include <QObject>
#include <QWidget>
#include <QLineEdit>
#include <QPushButton>
#include <QTextBrowser>class DialogConnect : public QDialog
{Q_OBJECTsignals:void sendMessage(QString &Message);
public:DialogConnect();QPushButton * btn_Open;QPushButton * btn_Send;QLineEdit * line;QTextBrowser * receive;//dialog2 * x = nullptr;public slots:void receiveMessage(QString &Message);
};#endif // DIALOGCONNECT_H

#include "dialogconnect.h"#include <QGridLayout>
#include <QPushButton>
#include <QDebug>
#include"dialog2.h"DialogConnect::DialogConnect()
{btn_Open = new QPushButton("打开",this);btn_Send = new QPushButton("发送",this);line = new QLineEdit("",this);receive = new QTextBrowser();QGridLayout * grid = new QGridLayout;grid->addWidget(btn_Open,1,1,1,2,Qt::Alignment());grid->addWidget(receive,2,1,2,2,Qt::Alignment());grid->addWidget(btn_Send,5,1,1,2,Qt::Alignment());grid->addWidget(line,4,1,1,4,Qt::Alignment());this->setLayout(grid);//    connect(DialogConnect::btn_Open,&QPushButton::clicked,this,[=]{
//      if(x == nullptr){
//          x = new dialog2;
//          qDebug()<<"已经打开";
//          x->show();
//      }//    });connect(btn_Send,&QPushButton::clicked,[=]{QString x = this->line->text();emit sendMessage(x);});}void DialogConnect::receiveMessage(QString &Message)
{this->receive->setPlainText(Message);}

dialog2

#ifndef DIALOG2_H
#define DIALOG2_H#include <QDialog>
#include <QLineEdit>
#include <QObject>
#include <QTextBrowser>
#include <QWidget>class dialog2 : public QDialog
{Q_OBJECT
signals:void sendMessage(QString &Message);
public:dialog2();QPushButton * btn_Send;QLineEdit * line;QTextBrowser * receive;public slots:void receiveMessage(QString &Message);};#endif // DIALOG2_H

#include "dialog2.h"#include <QGridLayout>
#include <QPushButton>dialog2::dialog2()
{btn_Send = new QPushButton("发送",this);line = new QLineEdit("",this);receive = new QTextBrowser();QGridLayout * grid = new QGridLayout;grid->addWidget(receive,2,1,2,2,Qt::Alignment());grid->addWidget(btn_Send,5,1,1,2,Qt::Alignment());grid->addWidget(line,4,1,1,4,Qt::Alignment());this->setLayout(grid);connect(btn_Send,&QPushButton::clicked,[=]{QString x = this->line->text();emit sendMessage(x);});}void dialog2::receiveMessage(QString &Message)
{this->receive->setPlainText(Message);
}

最后在mian函数里面绑定信号槽,并且show出来

#include "dialog.h"
#include "test2.h"
#include "dialogconnect.h"
#include "dialog2.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);DialogConnect * w = new DialogConnect ;dialog2 * w1 = new dialog2;w->show();QObject::connect(w->btn_Open,&QPushButton::clicked,[=]{w1->show();});QObject::connect(w,&DialogConnect::sendMessage,w1,&dialog2::receiveMessage);QObject::connect(w1,&dialog2::sendMessage,w,&DialogConnect::receiveMessage);return a.exec();
}