Qt实现简易计算器

#ifndef CALC_H
#define CALC_H

#include <QtWidgets/QMainWindow>
#include "ui_calc.h"

class calc : public QMainWindow
{
Q_OBJECT

public:
calc(QWidget *parent = 0);
~calc();
double x;
double y;
char ch;
bool flag;

private:
Ui::calcClass ui;
private slots:
void on_pushButton_0_clicked();
void on_pushButton_1_clicked();
void on_pushButton_2_clicked();
void on_pushButton_3_clicked();
void on_pushButton_4_clicked();
void on_pushButton_5_clicked();
void on_pushButton_6_clicked();
void on_pushButton_7_clicked();
void on_pushButton_8_clicked();
void on_pushButton_9_clicked();
void on_pushButton_divide_clicked();
void on_pushButton_equal_clicked();
void on_pushButton_multi_clicked();
void on_pushButton_plus_clicked();
void on_pushButton_point_clicked();
void on_pushButton_sub_clicked();
};

#endif // CALC_H

#include "calc.h"
#include <QString>
#include <QMessageBox>

calc::calc(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this);
x = 0;
y = 0;
flag = false;
setWindowTitle(QStringLiteral("计算器"));

}

calc::~calc()
{

}

void calc::on_pushButton_0_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("0");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("0"));
}
}
void calc::on_pushButton_1_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("1");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("1"));
}
}
void calc::on_pushButton_2_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("2");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("2"));
}
}
void calc::on_pushButton_3_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("3");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("3"));
}
}
void calc::on_pushButton_4_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("4");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("4"));
}
}
void calc::on_pushButton_5_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("5");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("5"));
}
}
void calc::on_pushButton_6_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("6");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("6"));
}
}
void calc::on_pushButton_7_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("7");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("7"));
}
}
void calc::on_pushButton_8_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("8");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("8"));
}
}
void calc::on_pushButton_9_clicked()
{
if (flag)
{
ui.label_2->clear();
flag = false;
}
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString("9");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText(QString("9"));
}
}
void calc::on_pushButton_divide_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL)
{
ui.label_2->clear();
ui.label_2->setText("/");
ch = '/';
x = temp.toDouble();
}
else
{
ui.label_2->setText("error");
}
}
void calc::on_pushButton_equal_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL)
{
flag = true;
y = temp.toDouble();
switch (ch)
{
case '+' :
ui.label_2->setText(QString("%1").arg(x + y));
break;
case '-' :
ui.label_2->setText(QString("%1").arg(x - y));
break;
case '*' :
ui.label_2->setText(QString("%1").arg(x * y));
break;
case '/' :
ui.label_2->setText(QString("%1").arg(x / y));
break;
default:
break;
}
}
else
{
ui.label_2->setText("error");
}
}
void calc::on_pushButton_multi_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL)
{
ui.label_2->clear();
ui.label_2->setText("*");
x = temp.toDouble();
ch = '*';
}
else
{
ui.label_2->setText("error");
}
}
void calc::on_pushButton_plus_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL)
{
ui.label_2->clear();
ui.label_2->setText("+");
x = temp.toDouble();
ch = '+';
}
else
{
ui.label_2->setText("error");
}
}
void calc::on_pushButton_point_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" && temp != NULL && (temp != "+" && temp != "-" && temp != "*" && temp != "/"))
{
temp += QString(".");
ui.label_2->setText(temp);
}

else
{
ui.label_2->setText("error");
}
}
void calc::on_pushButton_sub_clicked()
{
QString temp = ui.label_2->text();
if (temp != "" || temp != NULL)
{
ui.label_2->clear();
ui.label_2->setText("-");
x = temp.toDouble();
ch = '-';
}
else
{
ui.label_2->setText("error");
}
}