QT QT练习一

界面中通过三个 QLineEdit控件，一个QPushButton实现+ - * /四则运算，点击pushbutton后将运算结果显示在QLabel控件上。

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QLineEdit>
#include <QPushButton>
#include <QLabel>

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = 0);
    ~Widget();
private:
    QLineEdit * edit1;
    QLineEdit * edit2;
    QLineEdit * edit3;
    QPushButton * btn1;
    QLabel *label1;
    double GetRes(int num1,char ch,int num2);
private slots:
    void add();
};

#endif // WIDGET_H

#include "widget.h"
#include <QGridLayout>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    edit1=new QLineEdit(this);
    edit2=new QLineEdit(this);
    edit3=new QLineEdit(this);
    btn1=new QPushButton(this);
    btn1->setText("计算");
    label1=new QLabel(this);
    label1->setText("result");
    QGridLayout * layout1=new QGridLayout(this);
    layout1->addWidget(edit1,0,0);
    layout1->addWidget(edit2,0,1);
    layout1->addWidget(edit3,0,2);
    layout1->addWidget(btn1,1,0);
    layout1->addWidget(label1,1,1);
    //注册按钮点击事件
    connect(btn1,SIGNAL(clicked()),this,SLOT(add()));
}

//按钮点击事件
void Widget::add()
{
    //获取第一个数
    QString s1=edit1->text();
    //获取操作符
    QString s2=edit2->text();
    //获取第三个数
    QString s3=edit3->text();
    //显示结果
    label1->setText(QString::number(GetRes(s1.toInt(),*(s2.toStdString().data()),s3.toInt())));
}

//计算结果
double Widget::GetRes(int num1,char ch,int num2)
{
    double res=0;
    switch(ch)
    {
    case ‘+‘:
        res=num1+num2;
        break;
    case ‘-‘:
        res=num1-num2;
        break;
    case ‘*‘:
        res=num1*num2;
        break;
    case ‘/‘:
        res=num1/num2;
        break;
    default:
        break;
    }
    return res;
}

Widget::~Widget()
{

}