QT实现四则运算计算器(QT实操1)

1.项目架构

1.图形化界面

​

2.widget.h​

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QString>
#include <QStack>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    void on_oneButton_clicked();

    void on_twoButton_clicked();

    void on_threeButton_clicked();

    void on_fourButton_clicked();

    void on_fiveButton_clicked();

    void on_sixButton_clicked();

    void on_sevenButton_clicked();

    void on_eightButton_clicked();

    void on_nineButton_clicked();

    void on_leftButton_clicked();

    void on_rightButton_clicked();

    void on_addButton_clicked();

    void on_reduceButton_clicked();

    void on_mulButton_clicked();

    void on_divButton_clicked();

    void on_zeroButton_clicked();

    void on_clearButton_clicked();

    void on_backButton_clicked();

    void on_equalButton_clicked();

    int evaluateExpression(const QString &expr);

    int applyOperator(double a, double b, QChar op);

private:
    Ui::Widget *ui;
    QString expression;
};
#endif // WIDGET_H

3.main.cpp​

#include "widget.h"

#include <QApplication>

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

3.widget.cpp​

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

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

    this->setMaximumSize(210,295);
    this->setMinimumSize(210,295);
    this->setWindowTitle("计算器");

    QFont f("仿宋",14);//字体对象
    ui->mainLineEdit->setFont(f);

    //按钮上放图片
    QIcon con("/data/wzh/QT/Qt_1/calculate/Back.png");
    ui->backButton->setIcon(con);

    //改变按钮背景色
    ui->equalButton->setStyleSheet("background:green");


}

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


void Widget::on_oneButton_clicked()
{
    expression += "1";
    ui->mainLineEdit->setText(expression);
}

void Widget::on_twoButton_clicked()
{
    expression += "2";
    ui->mainLineEdit->setText(expression);
}

void Widget::on_threeButton_clicked()
{
    expression += "3";
    ui->mainLineEdit->setText(expression);
}

void Widget::on_fourButton_clicked()
{
    expression += "4";
    ui->mainLineEdit->setText(expression);
}

void Widget::on_fiveButton_clicked()
{
    expression += "5";
    ui->mainLineEdit->setText(expression);
}

void Widget::on_sixButton_clicked()
{
    expression += "6";
    ui->mainLineEdit->setText(expression