Qt實現一個簡單的計算器

一、UI介面版

執行效果：輸入num1和num2選擇+-*/點選計算即可

UI介面設計：

3個lineEdit（lineEditNum1，lineEditNum2，lineEditSum）

2個PushButton（buttonClear，ButtonCalc）

1個comboBox

1個label

佈局：

3個lineEdit和1個comboBox、1個label水平佈局

2個PushButton和一個彈簧水平佈局

最後整體佈局即可

main.cpp

#include "mainwindow.h"
#include <QApplication>
​
int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  MainWindow w;
  w.show();
​
  return a.exec();
}
​
 

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QMessageBox>
​
MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
}
​
MainWindow::~MainWindow()
{
  delete ui;
}
​
​
void MainWindow::on_buttonCalc_clicked()
{
  double num1 = ui->lineEditNum1->text().toDouble();//獲取num1的值
  double num2 = ui->lineEditNum2->text().toDouble();//獲取num2的值
  uint8_t index = ui->comboBox->currentIndex();  //獲取下拉框的下標0 +, 1 - ,2 *, 3 /
  double result = 0.0;
​
  switch (index) {
  case 0:
    result = num1 + num2;
    break;
  case 1:
    result = num1 - num2;
    break;
  case 2:
    result = num1 * num2;
    break;
  case 3:
    if(num2 == 0)
     {
      QMessageBox::about(this,"注意","除數不能為0");
      return;
     }
    result = num1 / num2;
    break;
  default:
    break;
   }
  ui->lineEditSum->setText(QString::number(result));
}
​
void MainWindow::on_buttonClear_clicked()
{
  ui->lineEditNum1->clear();
  ui->lineEditNum2->clear();
  ui->lineEditSum->clear();
}
 

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 = 0);
  ~MainWindow();
​
private slots:
​
  void on_buttonCalc_clicked();//計算結果槽函式
​
  void on_buttonClear_clicked();//清除輸入框槽函式
​
private:
  Ui::MainWindow *ui;
};
​
#endif // MAINWINDOW_H
​
 

二、純程式碼版

注：只能兩個數單獨加減乘除，不能連續運算，按‘ = ’重新開始兩個數運算

main.cpp

#include "calc.h"
#include <QApplication>
​
int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  Calc w;
  w.show();
​
  return a.exec();
}

calc.cpp

#include "calc.h"
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QLineEdit>
#include <QSizePolicy>
#include <QDebug>
​
Calc::Calc(QWidget *parent) :
  QWidget(parent)
{
  //獲取字型QFont
  QFont font = this->font();
  font.setPixelSize(30);
  this->setFont(font);
​
  //儲存鍵盤值
  QString keys="789-456*123/0.+=";
  QVBoxLayout *vbox = new QVBoxLayout();
​
  QSizePolicy qsPolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
  for(int i=0; i<4; i++)
   {
    QHBoxLayout *hbox = new QHBoxLayout();
    for(int j=0; j<4; j++)
     {
      buttons[i*4+j] = new QToolButton(this);
      //設定文字
      buttons[i*4+j]->setText(keys.mid(i*4+j, 1));
      hbox->addWidget(buttons[i*4+j]);
​
      //策略設定
      buttons[i*4+j]->setSizePolicy(qsPolicy);
​
      //把按鈕觸發訊號關聯槽函式
      connect(buttons[i*4+j], SIGNAL(clicked(bool)),this, SLOT(buttons_chick()));
     }
    //把水平佈局管理器新增到垂直佈局管理器中
    vbox->addLayout(hbox);
   }
​
  //建立一個輸入框
  edit = new QLineEdit(this);
  edit->setSizePolicy(qsPolicy);
  edit->setMaximumHeight(60);
  edit->setAlignment(Qt::AlignRight);
​
​
  QVBoxLayout *allVbox = new QVBoxLayout(this);
  allVbox->addWidget(edit);
  allVbox->addLayout(vbox);
​
​
  //初始化
  firstNumber.clear();
  secondNumber.clear();
  calcflag = 0;
​
}
Calc::~Calc()
{
}
void Calc::input_data(QString str)
{
  if(calcflag == 0)
   {
    firstNumber.append(str);
    edit->setText(firstNumber);
   }else
   {
    secondNumber.append(str);
    edit->setText(secondNumber);
   }
}
​
void Calc::buttons_chick()
{
  //通過訊號傳送者獲取按鈕物件
  QToolButton *button = (QToolButton*)sender();
  //qDebug()
  QString str = button->text();
  QString datastr = ".0123456789";
  QStringList typestr;
  typestr<<"+"<<"-"<<"*"<<"/";
  if(datastr.indexOf(str) >= 0)//獲取按鍵值
   {
    input_data(str);  //輸入資料
   }else if(typestr.indexOf(str)>=0)
   {
    calcflag = typestr.indexOf(str)+1;//獲取運算子號type
   }else //=
   {
    double result = 0.0;
    switch (calcflag) {
    case 1:
      result = firstNumber.toDouble()+secondNumber.toDouble();
      break;
    case 2:
      result = firstNumber.toDouble()-secondNumber.toDouble();
      break;
    case 3:
      result = firstNumber.toDouble()*secondNumber.toDouble();
      break;
    case 4:
      result = firstNumber.toDouble()/secondNumber.toDouble();
      break;
    default:
      break;
     }
    edit->setText(QString::number(result));
    calcflag = 0;
    firstNumber.clear();
    secondNumber.clear();
   }
}

calc.h

#ifndef CALC_H
#define CALC_H
​
#include <QWidget>
#include <QToolButton>
#include <QLineEdit>
​
class Calc : public QWidget
{
  Q_OBJECT
public:
  explicit Calc(QWidget *parent = 0);
  ~Calc();
  void input_data(QString str);
  
protected slots:
  void buttons_chick();//按鍵槽函式
​
private:
  
  QToolButton *buttons[16];  //按鈕陣列
  QLineEdit *edit;      //輸入框
  QString firstNumber;    //記錄輸入第一個數值
  QString secondNumber;    //記錄輸入第一個數值
  int calcflag;        //1-add， 2-sub, 3-mul, 4-div
};
​
#endif // CALC_H

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