QT 写 计算器

widget.h  文件

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include<QMessageBox>
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

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

private slots:
    void on_pushButton_clicked();

    void on_clearButton_clicked();

private:
    Ui::Widget *ui;

};

#endif // WIDGET_H

main.c

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

widget.cpp

#include "widget.h"
#include "ui_widget.h"

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

}

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

void Widget::on_pushButton_clicked()
{
    float arg1 = ui->lineEdit_1->text().toFloat();
    float arg2 = ui->lineEdit_2->text().toFloat();
    float result;
    //开始做判断
    if(ui->comboBox->currentText()=="+")
    {
        result = arg1+arg2;
    }
    else if(ui->comboBox->currentText()=="-")
    {
        result = arg1 -arg2;
    }else if(ui->comboBox->currentText()=="*")
    {
        result = arg1 * arg2;
    }else
    {
        if(arg2 == 0)
        {
            QMessageBox::warning(this,"警告","除数不能为0");
            on_clearButton_clicked();
            return ;
        }
        result = arg1/arg2;
    }
    //将运算结果显示到label上
    //将float转换成Qstring
    ui->resultLabel->setText(QString::number(result));

}

void Widget::on_clearButton_clicked()
{
    ui->lineEdit_1->clear();
    ui->lineEdit_2->clear();
    ui->resultLabel->clear();
}

ui界面如下