基于QT5的计算器简单实现

本人实验室培训作业

需求：实现必要的计算器功能，合理化布局

UI布局：

逻辑思维：由于组件中的text()值多为QSTring类型，

1.将槽的操作都写成，往一个大字符串追加信息

2.将字符串解析，利用栈实现数据的先后弹出，操作符的优先顺序

具体实现代码如下：

由于代码中注释足够详细，不再做文字说明：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    QString numInfo;
    void caculate();
    int is_First(char a, char b);
    struct node{
        int flag;
        union{
            double a;
            char  op;
    }num;

//public slots:
//空写slots,编译时会出错，导致无法编译，
//下次务必不要踩雷

};


private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

mainwindow.cpp

//9月29号9:12
//10月3号0:13
//完成基本功能，运算逻辑均正确
//至于科学计算器其它复杂的功能，可日后添加

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "QPixmap"
#include "QPushButton"
#include "QIcon"
#include "QPixmap"
#include "QSize"
#include "QDebug"
#include "QFont"
#include "QVector"
#include "QStack"
#include "math.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    //设置固定尺寸
    this->setFixedSize(1061,800);
    this->setWindowIcon(QPixmap(":/res/caculater_icon.jpg"));
    this->setWindowTitle("爷的科学计算器");
    //计算符号图标
    //Qicon会自动缩小，这里用Qpixmap先放大
    ui->ride_btn->setIconSize(QSize(100,100));
    ui->ride_btn->setIcon(QIcon(QPixmap(":/res/ride.png")));

    ui->plus_btn->setIconSize(QSize(100,100));
    ui->plus_btn->setIcon(QIcon(QPixmap(":/res/plus.png")));

    ui->reduce_btn->setIconSize(QSize(100,100));
    ui->reduce_btn->setIcon(QIcon(QPixmap(":/res/reduce.png")));

    ui->equal_btn->setIconSize(QSize(100,100));
    ui->equal_btn->setIcon(QIcon(QPixmap(":/res/equal.png")));

    ui->clear_btn->setIconSize(QSize(100,100));
    ui->clear_btn->setIcon(QIcon(QPixmap(":/res/clear.png")));

    ui->back_btn->setIconSize(QSize(100,100));
    ui->back_btn->setIcon(QIcon(QPixmap(":/res/back.png")));

    ui->division_btn->setIconSize(QSize(100,100));
    ui->division_btn->setIcon(QIcon(QPixmap(":/res/division.png")));

    ui->left_btn->setIconSize(QSize(100,100));
    ui->left_btn->setIcon(QIcon(QPixmap(":/res/left.png")));

    ui->right_btn->setIconSize(QSize(100,100));
    ui->right_btn->setIcon(QIcon(QPixmap(":/res/right.png")));

    ui->mod_btn->setIconSize(QSize(100,100));
    ui->mod_btn->setIcon(QIcon(QPixmap(":/res/mod.png")));

    if(this->ui->history_label->text() == ""){
        this->ui->history_label->setText("尚无历史记录");
    }

    //上面发现label字体太小
    QFont font;
    font.setPointSize(20);
    ui->screen_label->setFont(font);

    //通过按钮的text获得按钮代表数字
    this->numInfo = "";
    //写好获取text值，追加字符串之后
    //将btn的clicked与this.slots{}连接
    //不写槽了，用lamda表达式直接模式粘贴复制
    //可以提模板，但是已经写完了
    connect(ui->num1_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num1_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num2_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num2_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num3_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num3_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num4_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num4_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num5_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num5_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num6_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num6_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num7_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num7_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num8_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num8_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num9_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num9_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;

    });
    connect(ui->num0_btn,&QPushButton::clicked,[=](){

            this->numInfo += this->ui->num0_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;


    });
    connect(ui->point_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->point_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }

    });
    connect(ui->equal_btn ,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->caculate();
            this->ui->history_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->left_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->left_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->right_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->right_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->plus_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->plus_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->ride_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->ride_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->reduce_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->reduce_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->division_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->division_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
    connect(ui->clear_btn,&QPushButton::clicked,[=](){
        this->numInfo = "";
        this->ui->screen_label->setText(this->numInfo);
});
    connect(ui->back_btn,&QPushButton::clicked,[=](){
        this->numInfo = this->numInfo.left(this->numInfo.size()-1);
        ui->screen_label->setText(this->numInfo);
});
    connect(ui->mod_btn,&QPushButton::clicked,[=](){
        if(this->numInfo != " "){
            this->numInfo += this->ui->mod_btn->text();
            this->ui->screen_label->setText(this->numInfo);
            qDebug() << this->numInfo <<endl;
        }
    });
}
//字符串算式解析的方法实现
void MainWindow::caculate(){

//    QVector<double> numlist;
    node nodeList[20];
    double num = 0;
    //设置位置
    int position = 0;
    //设置浮点数标志
    int float_flog = 0;
    //浮点数的小数数量，整数数量
    int num_of_float = 0;
    int num_of_int = 0;
    //获取字符串长度
    int len = this->numInfo.size();
    //老子不用vector了
//    double numlist[len];
    //提取整数
    while(position < len){
        if(numInfo[position] >= '0' && numInfo[position] <= '9'){
            if(!float_flog){
                //将字符串的元素转化为ASCII码
                /*返回相当于QChar的拉丁语-1字符，或0。这主要用于非国际化软件。
                注意：不可能区分非拉丁1字符和拉丁10（NUL）字符。更喜欢使用unicode（），它没有这种模糊性。
                百度结果*/
                num = num*10 + (numInfo[position].toLatin1()-'0');
                ++position;
            }
            else{
                //这一块是算小数部分
                double p = 1;
                for(int k = 0; k < num_of_float;k++){
                    p *= 0.1;
                }
                num += (numInfo[position].toLatin1()-'0')*p;
                num_of_float++;
                ++position;
            }
        }
        //这块是读到小数点，设置标志，设置小数数量（含小数点）
        else if (numInfo[position] == '.') {
            float_flog = 1;
            num_of_float = 1;
            ++position;
        }
        //下面是读到运算符的情况
        else {
                if(num){
                    nodeList[num_of_int].flag = 0;
                    nodeList[num_of_int].num.a = num;
                    qDebug() <<nodeList[num_of_int].num.a;
                    num = 0;
                    ++num_of_int;
                    float_flog = 0;
                    num_of_float = 0;
                    //莫名其妙的bug
//                    qDebug() << QString("%1").arg((numlist.at(1)+numlist.at(2)));
//                    this->numInfo += QString("%1").arg((numlist.at(1)+numlist.at(2)));

//                    while(i>=1){
//                        qDebug() << QString("%1").arg((numlist[i]+numlist[i-1]));
//                        break;
//                    }

            }
                nodeList[num_of_int].flag = 1;
                nodeList[num_of_int].num.op = numInfo[position].toLatin1();
                ++num_of_int;
                ++position;
        }
    }
    //最后一个操作数
    if(num){
        nodeList[num_of_int].flag = 0;
        nodeList[num_of_int].num.a = num;
        qDebug() <<nodeList[num_of_int].num.a;
        ++num_of_int;
        num = 0;
    }
    //利用栈的存储特性，将符号存入并按后缀的顺序读出
    //创建一个Qstack类型的，保存操作符的栈
    QStack<node> signList;
    //临时性出栈操作符
    node temporarySign_node[20];
    int j = 0;
    for(int m = 0; m < num_of_int;){
        if(nodeList[m].flag){

            if(signList.isEmpty()){

                signList.push(nodeList[m++]);
            }
            else{
                node temp = signList.top();
                //判断运算符优先级
                int res = is_First(temp.num.op,nodeList[m].num.op);
                switch (res) {
                case -1:
                    signList.push(nodeList[m++]);
                    break;
                case 1:
                    temporarySign_node[j++] = signList.top();
                    signList.pop();
                    break;
                default:
                    signList.pop();
                    m++;
                    break;
                }

            }
        }
        else {
            temporarySign_node[j++] = nodeList[m++];
        }

    }
    //处理算式中的括号
while(!signList.isEmpty()){
        node tem = signList.top();
        if(tem.num.op != '(' &&tem.num.op != ')'){
            temporarySign_node[j++] = tem;
        }
        signList.pop();
}

QStack<double> last_signList;
double d1 = 0,d2 = 0;
for(int n = 0; n < j ; n++){
    //遇到符号弹出数字，弹出前两个数字
    if(temporarySign_node[n].flag){

        d2 = last_signList.top();
        last_signList.pop();
        d1 = last_signList.top();
        last_signList.pop();

        switch(temporarySign_node[n].num.op)
                {
                    case '+':
                            d1 += d2;
                            break;
                    case '-':
                            d1 -= d2;
                            break;
                    case '*':
                            d1 *= d2;
                            break;
                    case '/':
                            d1 /= d2;
                            break;
                    case '%':
            //注意，这块是浮点数去模，一定要注意用fmod方法，头文件为math.h
            //切记不要再次踩雷
                            d1 = fmod(d1,d2);
                            break;
                     default:
                             break;
                }
                last_signList.push(d1);
    }
    else
        {
            last_signList.push(temporarySign_node[n].num.a);
        }

}
    qDebug() << d1;
    this->numInfo += '=';
    this->numInfo += QString::number(d1);
    this->ui->screen_label->setText(this->numInfo);
}

//返回整形标志的运算符优先级比对结果
int MainWindow::is_First(char a, char b){
    char aim[7][8] = {{ ">><<<>>" },{ ">><<<>>" },{ ">>>><>>" },{ ">>>><>>" },{ "<<<<<=1" },{ ">>>>1>>" },{ "<<<<<1=" }};
        char sta[7] = { '+','-','*','/','(',')','#' };
        char result;
        int i,pa,pb;
        for (i = 0; i<6; i++)
              {
                 if (a == sta[i])
                 {
                     pa = i;
                 }
                 if (b == sta[i])
                 {
                     pb = i;
                 }
              }
        result = aim[pa][pb];
        if(result == '>')return 1;
        else if(result == '<')return -1;
        else return 0;
}
MainWindow::~MainWindow()
{
    delete ui;
}

不可描述的雷：

第一遍运行时，系统会一直报构建方法出错，还不告诉你第几行出错，经查询，把build_debug的文件夹删了就可通顺运行，原因是第一遍程序已经qmake，后面在debug后，再次qmake，build_debug文件夹中的debug文件会与程序重现qmake的步骤相冲突

运行结果图：

最大的点：

可以用toDoule方法直接解析字符串算式，不用上面那种繁琐的方法，但是！！！

我已经写完了，淦