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C++结合QT实现带有优先级的计算器功能

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我是靠谱客的博主 平淡小馒头，最近开发中收集的这篇文章主要介绍C++结合QT实现带有优先级的计算器功能，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

代码

MyCalculator.h

#pragma once

#include <QtWidgets/QMainWindow>
#include <QStack>
#include <QString>
#include "ui_MyCalculator.h"

class MyCalculator : public QMainWindow
{
  Q_OBJECT

public:
  MyCalculator(QWidget *parent = Q_NULLPTR);
	
/*	void setnum1(int num);
	void setnum2(int num);
	void setflag(int f);
	int calculartor();
*/


private slots:
	void on_number_Button_clicked();
	void on_action_Button_clicked();
	void on_comma_Button_clicked();
	void on_action_Button_c_clicked();
	void on_action_Button_d_clicked();
	void on_action_Button_e_clicked();

/*
	void on_action_Button_equal_clicked();
	void on_number_Button_clicked();
	void on_action_Button_clicked();
	void on_action_Button_c_clicked();
*/

private:
  Ui::MyCalculatorClass ui;

};

MyCalculator.main

#include "MyCalculator.h"
#include <QtWidgets/QApplication>

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

MyCalculator.cpp

#include "MyCalculator.h"

#include<iostream>
using namespace std;
#include<stack>
#include<vector>
#include<cstdlib>
#include<limits.h>

MyCalculator::MyCalculator(QWidget *parent)
  : QMainWindow(parent)
{
  ui.setupUi(this);
	setWindowTitle(QStringLiteral("计算器"));
	ui.textBrowser->setFontPointSize(28);

	connect(ui.pushButton0, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton1, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton2, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton3, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton4, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton5, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton6, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton7, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton8, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton9, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));

	connect(ui.pushButton_add, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_div, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_mul, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_sub, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_right, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_left, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_dian, SIGNAL(clicked()), this, SLOT(on_comma_Button_clicked()));


	connect(ui.pushButton_del, SIGNAL(clicked()), this, SLOT(on_action_Button_d_clicked()));
	connect(ui.pushButton_re, SIGNAL(clicked()), this, SLOT(on_action_Button_c_clicked()));
	connect(ui.pushButton_equ, SIGNAL(clicked()), this, SLOT(on_action_Button_e_clicked()));
	/*
	//没有优先级的计算器
	connect(ui.pushButton0, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton1, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton2, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton3, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton4, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton5, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton6, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton7, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton8, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));
	connect(ui.pushButton9, SIGNAL(clicked()), this, SLOT(on_number_Button_clicked()));

	connect(ui.pushButton_add, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_div, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_mul, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));
	connect(ui.pushButton_sub, SIGNAL(clicked()), this, SLOT(on_action_Button_clicked()));

	connect(ui.pushButton_re, SIGNAL(clicked()), this, SLOT(on_action_Button_c_clicked()));

	connect(ui.pushButton_equ, SIGNAL(clicked()), this, SLOT(on_action_Button_equal_clicked()));
	*/

}
void MyCalculator::on_number_Button_clicked()
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender());
	QString number = btn->text();
	QString ss = ui.textBrowser->toPlainText();
	ui.textBrowser->clear();
	ui.textBrowser->append(ss + number);
}
void MyCalculator::on_action_Button_clicked()//操作符
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender());
	QString action = btn->text();
	QString ss = ui.textBrowser->toPlainText();
	ui.textBrowser->clear();
	ui.textBrowser->append(ss + action);
}
void MyCalculator::on_comma_Button_clicked()//小数点
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender());
	QString action = btn->text();
	QString ss = ui.textBrowser->toPlainText();
	ui.textBrowser->clear();
	ui.textBrowser->append(ss + action);
}
void MyCalculator::on_action_Button_c_clicked()//重置输入框里的内容
{
	ui.textBrowser->clear();
}
void MyCalculator::on_action_Button_d_clicked()//删除表达式中最后一个符号
{
	QString ss = ui.textBrowser->toPlainText();//在一行
	ss = ss.left(ss.length() - 1);
	ui.textBrowser->clear();
	ui.textBrowser->setText(ss);
}
bool isNum(QString ch)
{
	if (ch >= '0' && ch <= '9' || ch == '.')
		return true;
	else
		return false;
}
bool isOperate(QString ch)
{
	if (ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '(' || ch == ')' )
		return true;
	else
		return false;
}
int level(QString ch) {//优先级设置
	if(ch == '(')
		return 5;
	else if (ch == '*' || ch== '/') 
		return 4;
	else if (ch == '+' || ch == '-')
		return 3;
	else if (ch == ')')
		return 2;
}
double calcu(double a ,double b, QString c)
{
	double result = 0;
	if (c == '+')
		result = b + a;
	else if (c == '-')
		result = b - a;
	else if (c == '*')
		result = b * a;
	else if (c == '/')
		result = b / a;
	else
		result = INT_MAX;
	return result;
}
double getjieguo(QString input)
{
	QStack<double> Num;
	QStack<QString> Act;
	int a = input.length();
	for(int i=0;i< a;i++)
	{
		int flag = 0;//用来判断是否是数字
		int xiaoshu = 1;//用来判断是否是小数部分
		double number = 0;//暂存数字
		QString frist = input.left(1);
		while (isNum(frist))				//连续的数字转化为一个整数
		{
			if (frist == '.' || xiaoshu == 2)
			{
				number = frist.toDouble() / 10 + number;
				xiaoshu = 2;
			}
			else
			{
				number = number * 10 + frist.toInt();
			}
			input = input.right(input.length() - 1);
			frist = input.left(1);
			flag = 1;
		}
		if (flag == 1)
			Num.push(number);

		if (isOperate(frist))
		{
			if (!Act.empty() && (level(Act.top()) > level(frist)))
			{
					double a = Num.pop();
					double b = Num.pop();
					QString c = Act.pop();
					double result = calcu(a, b, c);
					Num.push(result);
					if (frist != ')')
						Act.push(frist);
					input = input.right(input.length() - 1);
					frist = input.left(1);
			}
			else if (!Act.empty() && (level(Act.top()) <= level(frist)))
			{
				if (frist != '(')
					Act.push(frist);
				input = input.right(input.length() - 1);
				frist = input.left(1);
			}
			else if(Act.empty())				//操作符第一次入符号栈
			{
				Act.push(frist);
				input = input.right(input.length() - 1);
				frist = input.left(1);
			}
		}
		if (frist == '=')//支持得到结果后仍可以继续运算
		{
			Num.clear();
			Act.clear();
			input = input.right(input.length() - 1);
			frist = input.left(1);
		}

		if (i + 1 >= a)				//当表达式都进栈后，只要符号栈不为空就继续执行
		{
			while (!Act.empty())
			{
				double a1 = Num.pop();
				double b1 = Num.pop();
				QString c1 = Act.pop();
				double result = calcu(a1, b1, c1);
				Num.push(result);
			}
		}
	}

	return Num.top();

}
void MyCalculator::on_action_Button_e_clicked()
{
	QString input = ui.textBrowser->toPlainText();//将输入框里的内容给input
	double value = getjieguo(input);//将表达式传给getjieguo来将数字和操作符分别入对应的栈
	ui.textBrowser->clear();
	ui.textBrowser->append(input + "=" + QString::number(value));//将结果的类型由数字转化为QString

}
/*
void MyCalculator::setnum1(int num)
{
	num1 = num;
}
void MyCalculator::setnum2(int num)
{
	num2 = num;
}
void MyCalculator::setflag(int f)
{
	flag = f;
}
int MyCalculator::calculartor()
{
	int result = 0;
	if (flag == 1)
		result = num1 + num2;
	else if (flag == 2)
		result = num1 - num2;
	else if (flag == 3)
		result = num1 * num2;
	else if (flag == 4)
	{
		if (num2 == 0)
			setflag(5);
		else
			result = num1 / num2;
	}
	else
		result = 0;

	return result;
}

void MyCalculator::on_action_Button_c_clicked()
{
	ui.textBrowser->clear();
	setnum1(0);
	setnum2(0);
	setflag(0);
}

void MyCalculator::on_number_Button_clicked()
{
	QPushButton *btn = qobject_cast<QPushButton*>(sender());
	QString number = btn->text();
	QString ss = ui.textBrowser->toPlainText();
	ui.textBrowser->clear();
	ui.textBrowser->append(ss + number);
}

void MyCalculator::on_action_Button_clicked()
{
	int number = ui.textBrowser->toPlainText().toInt();
	setnum1(number);
	QPushButton *btn = qobject_cast<QPushButton*>(sender());
	QString action = btn->text();
	ui.textBrowser->clear();
	if (action == "+")
		setflag(1);
	else if (action == "-")
		setflag(2);
	else if (action == "*")
		setflag(3);
	else
		setflag(4);

}

void MyCalculator::on_action_Button_equal_clicked() {
	int number = ui.textBrowser->toPlainText().toInt();
	setnum2(number);
	int res = calculartor();
	ui.textBrowser->clear();
	if (flag == 5)
		ui.textBrowser->append(QStringLiteral("不能除于0，请重新输入"));
	else
		ui.textBrowser->append(QString::number(res));
}
*/

测试

表达式 结果
2*3+6-(1+3) 8
2+3*6-(1+3) 16
2+3*6-(1.3+5/2) 16.2

说明

  1. 自己的学习笔记 ，还有一些bug没有解决；
  2. 部分代码需要优化，重构；
  3. 没有实现输入错误表达式报错功能，需要输入正确的表达式。
  4. 不支持负数计算。
  5. 支持小数，加，减，乘，除，括号运算。

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