Flirting with QT Creator -Building First Desktop App

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 <QMessageBox>

QString strDisplay = "";

static double swapVar =0;

static bool isOpPending =false;

static bool isDispChangePending =false;

static char PendingOpr;

MainWindow::MainWindow(QWidget *parent) :

QMainWindow(parent),

ui(new Ui::MainWindow)

{

ui->setupUi(this);

ui->txtDisplay->setText("0");

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

ui->txtDisplay->setReadOnly(true);

}

MainWindow::~MainWindow()

{

delete ui;

}

/*Helper*/

void ShowMsg(QString strMsg)

{

QMessageBox msgBox;

msgBox.setText(strMsg);

msgBox.exec();

}

/*Clean Screen*/

void MainWindow::on_pbOprC_clicked()

{

ui->txtDisplay->setText("");

}

void MainWindow::on_pbOprAc_clicked()

{

strDisplay = "";

swapVar =0;

isOpPending =false;

isDispChangePending =false;

PendingOpr = '\0';

ui->txtDisplay->setText("");

}

void MainWindow::on_pbNum7_clicked()

{

QString numStr = QString::number(7);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

//strDisplay = QString::number(strDisplay.toDouble());

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum8_clicked()

{

QString numStr = QString::number(8);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum9_clicked()

{

QString numStr = QString::number(9);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum4_clicked()

{

QString numStr = QString::number(4);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum5_clicked()

{

QString numStr = QString::number(5);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum6_clicked()

{

QString numStr = QString::number(6);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum3_clicked()

{

QString numStr = QString::number(3);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum2_clicked()

{

QString numStr = QString::number(2);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum1_clicked()

{

QString numStr = QString::number(1);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbNum0_clicked()

{

QString numStr = QString::number(0);

if(isDispChangePending ==true){

strDisplay = numStr;

isDispChangePending =false;

}else{

strDisplay = ui->txtDisplay->toPlainText();

strDisplay = strDisplay + numStr;

if(strDisplay.contains(".") ==false)

{

strDisplay.remove( QRegExp("^[0]*") );

}

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

/*operation*/

void MainWindow::on_pbOprDivide_clicked()

{

/*new logic*/

if(isOpPending==true)

{

switch (PendingOpr) {

case '+':

swapVar = swapVar + strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case '-':

swapVar = swapVar - strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case 'x':

swapVar = swapVar * strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case '/':

if(strDisplay.toDouble() != 0)

{

swapVar = swapVar / strDisplay.toDouble();

strDisplay = QString::number(swapVar);

}

break;

default:

break;

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}else{

swapVar = strDisplay.toDouble();

}

//register to store value

swapVar = strDisplay.toDouble();

PendingOpr='/';

isOpPending =true;

isDispChangePending= true;

}

void MainWindow::on_pbOprMultiply_clicked()

{

/*new logic*/

if(isOpPending==true)

{

switch (PendingOpr) {

case '+':

swapVar = swapVar + strDisplay.toDouble();

strDisplay = QString::number(swapVar);\

break;

case '-':

swapVar = swapVar - strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case 'x':

swapVar = swapVar * strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case '/':

if(strDisplay.toDouble() != 0)

{

swapVar = swapVar / strDisplay.toDouble();

strDisplay = QString::number(swapVar);

}

break;

default:

break;

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}else{

swapVar = strDisplay.toDouble();

}

swapVar = strDisplay.toDouble();

PendingOpr='x';

isOpPending =true;

isDispChangePending= true;

}

void MainWindow::on_pbOprMinus_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

/*new logic*/

if(isOpPending==true)

{

switch (PendingOpr) {

case '+':

swapVar = swapVar + strDisplay.toDouble();

strDisplay = QString::number(swapVar);\

break;

case '-':

swapVar = swapVar - strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case 'x':

swapVar = swapVar * strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case '/':

if(strDisplay.toDouble() != 0)

{

swapVar = swapVar / strDisplay.toDouble();

strDisplay = QString::number(swapVar);

}

break;

default:

break;

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}else{

swapVar = strDisplay.toDouble();

}

/*old logic*/

swapVar = strDisplay.toDouble();

PendingOpr='-';

isOpPending =true;

isDispChangePending= true;

}

void MainWindow::on_pbOprPlus_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

/*new logic*/

if(isOpPending==true)

{

switch (PendingOpr) {

case '+':

swapVar = swapVar + strDisplay.toDouble();

strDisplay = QString::number(swapVar);\

break;

case '-':

swapVar = swapVar - strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case 'x':

swapVar = swapVar * strDisplay.toDouble();

strDisplay = QString::number(swapVar);

break;

case '/':

if(strDisplay.toDouble() != 0)

{

swapVar = swapVar / strDisplay.toDouble();

strDisplay = QString::number(swapVar);

}

break;

default:

break;

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}else{

swapVar = strDisplay.toDouble();

}

/*old logic*/

PendingOpr='+';

isOpPending =true;

isDispChangePending= true;

}

/**/

void MainWindow::on_pbOprPeriod_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

if(strDisplay.contains(".") ==false)

{

if(strDisplay=="")

{

strDisplay="0";

}

strDisplay = strDisplay + ".";

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

}

void MainWindow::on_pbOprSign_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

if(strDisplay.mid(0,1) == "-")

{

strDisplay = strDisplay.mid(1,strDisplay.length());

}else{

strDisplay = '-' + strDisplay;

}

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

void MainWindow::on_pbOprPercent_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

if(strDisplay!="")

{

strDisplay = QString::number(strDisplay.toDouble()/100);

ui->txtDisplay->setText(strDisplay);

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

}

}

/*get result*/

void MainWindow::on_pbOprEqual_clicked()

{

strDisplay = ui->txtDisplay->toPlainText();

switch (PendingOpr) {

case '+':

swapVar = swapVar + strDisplay.toDouble();

strDisplay = QString::number(swapVar);

ui->txtDisplay->setText(strDisplay);

break;

case '-':

swapVar = swapVar - strDisplay.toDouble();

strDisplay = QString::number(swapVar);

ui->txtDisplay->setText(strDisplay);

break;

case 'x':

swapVar = swapVar * strDisplay.toDouble();

strDisplay = QString::number(swapVar);

ui->txtDisplay->setText(strDisplay);

break;

case '/':

if(strDisplay.toDouble() != 0)

{

swapVar = swapVar / strDisplay.toDouble();

strDisplay = QString::number(swapVar);

ui->txtDisplay->setText(strDisplay);

}

break;

default:

break;

}

//common to call cases

ui->txtDisplay->setAlignment(Qt::AlignRight);

ui->txtDisplay->setFocus(Qt::OtherFocusReason);

swapVar =0;

isOpPending =false;

isDispChangePending =false;

PendingOpr = '\0';

}

/*see through register*/

void MainWindow::on_pushButton_clicked()

{

QString swapVarAsString = QString::number(swapVar);

ShowMsg(swapVarAsString);

}

GitHub Code :https://github.com/gitsangramdesai/qt-calc