安徽大学 数据结构课设 Qt 简易计算器（带括号的加减乘除）C++

下图为运行效果：

Qt version：5.14
IDE：Qt内置编译器
C++
表达式求值方法：中缀表达式转后缀表达式，后缀表达式求值。
后缀表达式求值比较简单，只需要熟练使用栈即可，就不展开描述了

源代码如下：带注释

畅所欲言，欢迎指正

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H //防止头文件重复包含

#include 
#include 

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow  //继承
{
    Q_OBJECT //宏，允许类中使用信号和槽的机制

public:
    MainWindow(QWidget *parent = 0);//有参构造（含默认值）
    ~MainWindow();

    void calculate();
    int judge(char a, char b);

private:
    QString s;
};

#endif // MAINWINDOW_H

cal.h

#ifndef FLOATNUMBER_H
#define FLOATNUMBER_H

#endif // FLOATNUMBER_H
#include 
using namespace std;

struct node{
    int flag;
    union{
        double fg; //flag==0时，为数字
        char op;    //flag==1时，为符号
    }exp;
};

mainwindow.cpp

#include "mainwindow.h"
#include  //按钮控件的头文件
#include 
#include 
#include 
#include 
#include 
#include 
#include "cal.h"

#define NUM_OF_NUMBER 20
#define NUMBERS 0
#define OPERATORS 1

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    s = "";
    setFixedSize(500,600);//固定窗口大小
    setWindowTitle("简易计算器");

   //声明按钮 设置字体颜色大小
       // QPushButton *button_delete = new QPushButton(this);
       // button_delete->setText("Del");
    QPushButton *button_delete = new QPushButton("DEL",this);
    button_delete->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_0 = new QPushButton("0",this);
    button_0->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_1 = new QPushButton("1",this);
    button_1->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
     QPushButton *button_2 = new QPushButton("2",this);
    button_2->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_3 = new QPushButton("3",this);
    button_3->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_4 = new QPushButton("4",this);
    button_4->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_5 = new QPushButton("5",this);
    button_5->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_6 = new QPushButton("6",this);
    button_6->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_7 = new QPushButton("7",this);
    button_7->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_8 = new QPushButton("8",this);
    button_8->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_9 = new QPushButton("9",this);
    button_9->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_add = new QPushButton("+",this);
    button_add->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_dec = new QPushButton("-",this);
    button_dec->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_mul = new QPushButton("*",this);
    button_mul->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_div = new QPushButton("/",this);
    button_div->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_clear = new QPushButton("CE",this);
    button_clear->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_equal = new QPushButton("=",this);
    button_equal->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_point = new QPushButton(".",this);
    button_point->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_left = new QPushButton("(",this);
    button_left->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");
    QPushButton *button_right = new QPushButton(")",this);
    button_right->setStyleSheet("QPushButton{font-family:'宋体';font-size:32px;color:rgb(0,0,0,255);}");


    //设置显示窗口
    QTextEdit *text = new QTextEdit(this);
    text->resize(440,90);//文本框重置大小
    text->move(30,10);//移动至此
    text->setFontPointSize(16);

    //设置显示学号
    QLabel *label=new QLabel("学号：2019******",this);
    label->move(20,540);
    label->resize(300,30);
    QFont font;
    font.setPointSize(12);
    label->setFont(font);

   //显示校名图片
   // QPixmap myPix("D:/A_Qt/Project/Calculate/hfut.png");
    QLabel *label_8=new QLabel(this);
    //label_8->setPixmap(myPix);
    label_8->move(230,525);
    label_8->resize(250,60);
    label_8->setStyleSheet("QLabel{border-image: url(:/ahut.png);}");
    label_8->setScaledContents(true);

    //布局
    button_1->resize(80,80);//按钮重置大小
    button_1->move(30,130);

    button_2->resize(80,80);
    button_2->move(120,130);

    button_3->resize(80,80);
    button_3->move(210,130);

    button_add->resize(80,80);//3
    button_add->move(300,130);

    button_4->resize(80,80);
    button_4->move(30,230);

    button_5->resize(80,80);
    button_5->move(120,230);

    button_6->resize(80,80);
    button_6->move(210,230);

    button_mul->resize(80,80);//7
    button_mul->move(300,230);

    button_7->resize(80,80);
    button_7->move(30,330);

    button_8->resize(80,80);
    button_8->move(120,330);

    button_9->resize(80,80);
    button_9->move(210,330);

    button_left->resize(80,80);
    button_left->move(300,330);

    button_0->resize(80,80);
    button_0->move(30,430);

    button_point->resize(80,80);
    button_point->move(120,430);

    button_equal->resize(80,80);
    button_equal->move(210,430);

    button_delete->resize(80,80);
    button_delete->move(300,430);

    button_dec->resize(80,80);
    button_dec->move(390,130);

    button_div->resize(80,80);
    button_div->move(390,230);

    button_right->resize(80,80);
    button_right->move(390,330);

    button_clear->resize(80,80);
    button_clear->move(390,430);


    //连接、处理信号
    //lambda表达式:用于定义并创建匿名的函数对象
    //信号的发送者 发送的信号 信号的接受者 处理的槽函数
    connect(button_0,&QPushButton::clicked,
            [=]()
            {
                //button_0->setText("123");
                s+="0";
                text->setText(s);
            }
            );
    connect(button_1,&QPushButton::clicked,
            [=]()
            {
                s+="1";
                text->setText(s);
            }
            );
    connect(button_2,&QPushButton::clicked,
            [=]()
            {
                s+="2";
                text->setText(s);
            }
            );
    connect(button_3,&QPushButton::clicked,
            [=]()
            {
                s+="3";
                text->setText(s);
            }
            );
    connect(button_4,&QPushButton::clicked,
            [=]()
            {
                s+="4";
                text->setText(s);
            }
            );
    connect(button_5,&QPushButton::clicked,
            [=]()
            {
                s+="5";
                text->setText(s);
            }
            );
    connect(button_6,&QPushButton::clicked,
            [=]()
            {
                s+="6";
                text->setText(s);
            }
            );
    connect(button_7,&QPushButton::clicked,
            [=]()
            {
                s+="7";
                text->setText(s);
            }
            );
    connect(button_8,&QPushButton::clicked,
            [=]()
            {
                s+="8";
                text->setText(s);
            }
            );
    connect(button_9,&QPushButton::clicked,
            [=]()
            {
                s+="9";
                text->setText(s);
            }
            );
    connect(button_add,&QPushButton::clicked,
            [=]()
            {
                s+="+";
                text->setText(s);
            }
            );
    connect(button_dec,&QPushButton::clicked,
            [=]()
            {
                s+="-";
                text->setText(s);
            }
            );
    connect(button_mul,&QPushButton::clicked,
            [=]()
            {
                s+="*";
                text->setText(s);
            }
            );
    connect(button_div,&QPushButton::clicked,
            [=]()
            {
                s+="/";
                text->setText(s);
            }
            );
    connect(button_clear,&QPushButton::clicked,
            [=]()
            {
                s="";
                text->setText(s);
            }
            );
    connect(button_left,&QPushButton::clicked,
            [=]()
            {
                s+="(";
                text->setText(s);
            }
            );
    connect(button_right,&QPushButton::clicked,
            [=]()
            {
                s+=")";
                text->setText(s);
            }
            );
    connect(button_point,&QPushButton::clicked,
            [=]()
            {
                s+=".";
                text->setText(s);
            }
            );
    connect(button_delete,&QPushButton::clicked,
            [=]()
            {
                s=s.left(s.length()-1);
                text->setText(s);
            }
            );
    connect(button_equal,&QPushButton::clicked,
            [=]()      //[=](){}实现函数内部的信号接收
            {
                MainWindow::calculate();
                text->setText(s);
            }
            );
}

MainWindow::~MainWindow()
{

}

void MainWindow::calculate()
{
    node Node[NUM_OF_NUMBER];
    double num1=0;
    int len=s.length();
    int i=0;            //标记字符串位置
    int num_of_point=0; //记录小数点个数
    int num_and_op=0;    //记录浮点数和操作符的个数
    int isfloat=0;      //标记为小数部分

    //读取表达式
    while(i<len){
        if((s[i]>='0'&&s[i]<='9')){
            if(!isfloat){   //整数部分
                num1=num1*10+(s[i].toLatin1()-'0');//s[i].toLatin1():QString类型转换为const char*（toLatin1）
                i++;
            }
            else{       //小数部分
                double per=1;
                for(int k=0;k<num_of_point;k++)
                    per*=0.1;
                num1+=(s[i].toLatin1()-'0')*per;
                num_of_point++;
                i++;
            }
        }
        else if(s[i].toLatin1()=='.'){     //读到小数点
            isfloat=1;
            num_of_point=1;
            i++;
        }
        else{       //读到操作符
            if(num1){
                Node[num_and_op].flag=NUMBERS;
                Node[num_and_op].exp.fg=num1;
                num1=0;
                num_and_op++;
                isfloat=0;
                num_of_point=0;
            }

            Node[num_and_op].flag=OPERATORS;
            Node[num_and_op].exp.op=s[i].toLatin1();
            ++num_and_op;
            ++i;
        }
    }
    if(num1){
        Node[num_and_op].flag=NUMBERS;
        Node[num_and_op].exp.fg=num1;
        ++num_and_op;
        num1=0;
    }

    //计算
    //中缀表达式转后缀表达式
    QStack<node> stack;
    node Node_1[NUM_OF_NUMBER];
    int j = 0;

    for(int i = 0; i < num_and_op;){
        if(Node[i].flag){//符号
            if(stack.isEmpty())
                stack.push_back(Node[i++]);
            else{
                node tem=stack.top();
                int ret=judge(tem.exp.op,Node[i].exp.op);
                switch (ret) {
                case -1:
                    stack.push_back(Node[i++]);
                    break;
                case 1:
                    Node_1[j++]=stack.top();
                    stack.pop();
                    break;
                default:
                    stack.pop();
                    i++;
                    break;
                }
            }
        }
        else{
            Node_1[j++]=Node[i++];
        }
    }
    for(;!stack.isEmpty();){
        node tem=stack.top();
        if(tem.exp.op != '('&& tem.exp.op != ')')
            Node_1[j++]=tem;
        stack.pop();
    }

    QStack<double> stack_1;
    double d1,d2;
    for(int i = 0; i < j; i++){
        if(Node_1[i].flag){     //操作符

            d2=stack_1.top();
            stack_1.pop();
            d1=stack_1.top();
            stack_1.pop();
            switch (Node_1[i].exp.op) {
            case '+':
                d1+=d2;
                break;
            case '-':
                d1-=d2;
                break;
            case '*':
                d1*=d2;
                break;
            case '/':
                d1/=d2;
                break;
            default:    //相当于#
                break;
            }
            stack_1.push_back(d1);
        }
        else{
            stack_1.push_back(Node_1[i].exp.fg);
        }
    }
    qDebug() << d1;
    s += '=';
    s += QString::number(d1);
}

//判断两个符号的优先级
int MainWindow::judge(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;
}

main.cpp

#include "mainwindow.h"

#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();//以顶层的方式弹出窗口控件
    return a.exec();
}

若嫌复制粘贴代码麻烦且会出错，这里有完整的项目文件
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