自学Qt_2,第一个应用程序

自学Qt第二天，自己写的一个简单的计算器，最后运行效果如下

利用Qt编写图形界面，一种是利用Qt-design，另外一种是代码编写

1.利用Qt-design编写，

Qt-design可以提高效率，其界面如下

代码如下：

mainwindow.h

#ifndef
MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>//是一个主窗口，它提供了构建用户应用程序界面的框架，

//它由ToolBars、Dock Widget、Central Widget、Status Bar组成

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

Q_OBJECT

public:

explicit MainWindow(QWidget *parent = 0);

~MainWindow();

private:

Ui::MainWindow *ui;

private slots:

void sum();

void mistake();

void ji();

void shang();

};

#endif // MAINWINDOW_H

mainwindow.cpp

#include
"mainwindow.h"

#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :

QMainWindow(parent),

ui(new Ui::MainWindow)

{

ui->setupUi(this);

QObject::connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(sum()));

QObject::connect(ui->pushButton_2,SIGNAL(clicked()),this,SLOT(mistake()));

QObject::connect(ui->pushButton_3,SIGNAL(clicked()),this,SLOT(ji
4000
()));

QObject::connect(ui->pushButton_4,SIGNAL(clicked()),this,SLOT(shang()));

}

MainWindow::~MainWindow()

{

delete ui;

}

void MainWindow::sum()

{

int first=ui->lineEdit->text().toInt();

int second=ui->lineEdit_2->text().toInt();

int result=first+second;

ui->lineEdit_3->setText(QString::number(result));

}

void MainWindow::mistake()

{

int first=ui->lineEdit_4->text().toInt();

int second=ui->lineEdit_5->text().toInt();

int result=first-second;

ui->lineEdit_6->setText(QString::number(result));

}

void MainWindow::ji()

{

int first=ui->lineEdit_7->text().toInt();

int second=ui->lineEdit_8->text().toInt();

int result=first*second;

ui->lineEdit_9->setText(QString::number(result));

}

void MainWindow::shang()

{

int first=ui->lineEdit_10->text().toInt();

int second=ui->lineEdit_11->text().toInt();

int result=first/second;

ui->lineEdit_12->setText(QString::number(result));

}

main.cpp

#include
"mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])//函数的入口，argc表示命令行数量，argv表示命令行数组

{

QApplication a(argc, argv);//必须的，任何qt的窗口系统被使用前都要创建QApplication对象

MainWindow w;//创建一个主窗口对象

w.show();//调用show显示主窗口

return a.exec();//

}

mainwindow.ui

<?xml version="1.0"encoding="UTF-8"?>

<ui version="4.0">

<class>MainWindow</class>

<widget class="QMainWindow" name="MainWindow">

<property name="geometry">

<rect>

<x>0</x>

<y>0</y>

<width>567</width>

<height>283</height>

</rect>

</property>

<property name="windowTitle">

<string>MainWindow</string>

</property>

<widget class="QWidget" name="centralWidget">

<widget class="QWidget" name="">

  <property name="geometry">

  <rect>

  <x>0</x>

<y>60</y>

<width>518</width>

<height>25</height>

  </rect>

</property>

<layout class="QHBoxLayout" name="horizontalLayout">

<item>

<widget class="QLineEdit" name="lineEdit"/>

</item>

<item>

<widget class="QLabel" name="label">

<property name="text">

<string>+</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_2"/>

</item>

<item>

<widget class="QLabel" name="label_2">

<property name="text">

<string>=</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_3"/>

</item>

<item>

<widget class="QPushButton" name="pushButton">

<property name="text">

<string>计算</string>

</property>

</widget>

</item>

</layout>

</widget>

<widget class="QWidget" name="">

  <property name="geometry">

  <rect>

  <x>0</x>

<y>100</y>

<width>518</width>

<height>25</height>

  </rect>

</property>

<layout class="QHBoxLayout" name="horizontalLayout_2">

<item>

<widget class="QLineEdit" name="lineEdit_4"/>

</item>

<item>

<widget class="QLabel" name="label_3">

<property name="text">

<string>-</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_5"/>

</item>

<item>

<widget class="QLabel" name="label_4">

<property name="text">

<string>=</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_6"/>

</item>

<item>

<widget class="QPushButton" name="pushButton_2">

<property name="text">

<string>计算</string>

</property>

</widget>

</item>

</layout>

</widget>

<widget class="QWidget" name="">

  <property name="geometry">

  <rect>

  <x>0</x>

<y>150</y>

<width>518</width>

<height>25</height>

  </rect>

</property>

<layout class="QHBoxLayout" name="horizontalLayout_3">

<item>

<widget class="QLineEdit" name="lineEdit_7"/>

</item>

<item>

<widget class="QLabel" name="label_5">

<property name="text">

<string>*</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_8"/>

</item>

<item>

<widget class="QLabel" name="label_6">

<property name="text">

<string>=</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_9"/>

</item>

<item>

<widget class="QPushButton" name="pushButton_3">

<property name="text">

<string>计算</string>

</property>

</widget>

</item>

</layout>

</widget>

<widget class="QWidget" name="">

  <property name="geometry">

  <rect>

  <x>0</x>

<y>190</y>

<width>518</width>

<height>25</height>

  </rect>

</property>

<layout class="QHBoxLayout" name="horizontalLayout_4">

<item>

<widget class="QLineEdit" name="lineEdit_10"/>

</item>

<item>

<widget class="QLabel" name="label_7">

<property name="text">

<string>/</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_11"/>

</item>

<item>

<widget class="QLabel" name="label_8">

<property name="text">

<string>=</string>

</property>

</widget>

</item>

<item>

<widget class="QLineEdit" name="lineEdit_12"/>

</item>

<item>

<widget class="QPushButton" name="pushButton_4">

<property name="text">

<string>计算</string>

</property>

</widget>

</item>

</layout>

</widget>

</widget>

<widget class="QMenuBar" name="menuBar">

 <property name="geometry">

 <rect>

 <x>0</x>

 <y>0</y>

 <width>567</width>

<height>23</height>

 </rect>

 </property>

</widget>

<widget class="QToolBar" name="mainToolBar">

<attribute name="toolBarArea">

<enum>TopToolBarArea</enum>

</attribute>

<attribute name="toolBarBreak">

<bool>false</bool>

</attribute>

</widget>

<widget class="QStatusBar" name="statusBar"/>

</widget>

<layoutdefault spacing="6" margin="11"/>

<resources/>

<connections/>

</ui>