Calculator source file

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>


//Global Variables
QString previous = "";
QString current = "";
QString awnser = "";
int decimals = 0;

// 1 = +
// 2 = *
// 3 = -
// 4 = /
int state = 0;

bool inputted = false;



MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::updateText()
{
    ui->label->setText(current);
}

//Basic Number buttons
void MainWindow::on_b_0_clicked()
{
    current += "0";
    MainWindow::updateText();
}

void MainWindow::on_b_1_clicked()
{
    current += "1";
    MainWindow::updateText();
}

void MainWindow::on_b_2_clicked()
{
    current += "2";
    MainWindow::updateText();
}

void MainWindow::on_b_3_clicked()
{
    current += "3";
    MainWindow::updateText();
}

void MainWindow::on_b_4_clicked()
{
    current += "4";
    MainWindow::updateText();
}

void MainWindow::on_b_5_clicked()
{
    current += "5";
    MainWindow::updateText();
}

void MainWindow::on_b_6_clicked()
{
    current += "6";
    MainWindow::updateText();
}

void MainWindow::on_b_7_clicked()
{
    current += "7";
    MainWindow::updateText();
}

void MainWindow::on_b_8_clicked()
{
    current += "8";
    MainWindow::updateText();
}

void MainWindow::on_b_9_clicked()
{
    current += "9";
    MainWindow::updateText();
}

//Adding a decimal to current
void MainWindow::on_b_decimal_clicked()
{
    if (decimals ==1)
    {
        QMessageBox::information(this,tr("Decimal error"),tr("You cannot have more than one decimal in a value"));
    }
    else {
        if (current == "")
        {
            current += "0.";
            decimals += 1;
        }
        else {
            current += ".";
            decimals += 1;
        }
        MainWindow::updateText();
    }

}

//Random number
void MainWindow::on_b_random_clicked()
{
    current = QString::number(qrand());
    MainWindow::updateText();
}



void MainWindow::on_b_plus_clicked()
{

    state = 1;
    previous = QString::number(previous.toFloat() + current.toFloat());
    current = "";
    decimals = 0;
    MainWindow::update();

}

void MainWindow::on_b_multiply_clicked()
{
    if (!inputted)
    {
        previous = QString::number(current.toFloat());
    }
    else {
        previous = QString::number(previous.toFloat() * current.toFloat());
    }
    inputted = true;
    state = 2;
    current = "";
    decimals = 0;
    MainWindow::update();
}

void MainWindow::on_b_divide_clicked()
{
    if (!inputted)
    {
        previous = QString::number(current.toFloat());
    }
    else {
        previous = QString::number(previous.toFloat() / current.toFloat());
    }
    inputted = true;
    state = 4;
    current = "";
    decimals = 0;
    MainWindow::update();
}

void MainWindow::on_b_minus_clicked()
{
    if (!inputted)
    {
        previous = QString::number(current.toFloat());
    }
    else {
        previous = QString::number(previous.toFloat() - current.toFloat());
    }
    inputted = true;
    state = 3;
    current = "";
    decimals = 0;
    MainWindow::update();
}

void MainWindow::on_b_equal_clicked()
{
    double temp = current.toFloat();
    if (state == 1)
    {
        current = QString::number(previous.toFloat() + temp);
        MainWindow::updateText();
    }
    else if (state == 2)
    {
        current = QString::number(previous.toFloat() * temp);
        MainWindow::updateText();
    }
    else if (state ==3)
    {
        current = QString::number(previous.toFloat() - temp);
        MainWindow::updateText();
    }
    else if (state = 4)
    {
        if (temp == 0)
        {
            current = "+ infinity and -Infinity (undertermined)";
        }
        else {
            current = QString::number(previous.toFloat() / temp);
        }
        MainWindow::updateText();
    }
    awnser = current;
}

void MainWindow::on_b_ans_clicked()
{
    current = awnser;
    MainWindow::updateText();
}

void MainWindow::on_b_ac_clicked()
{
    previous = "";
    current = "";
    decimals = 0;
    state = 0;
    inputted = false;
    MainWindow::updateText();
}

void MainWindow::on_b_del_clicked()
{
    current.remove(current.size()-1,1);
    MainWindow::updateText();
}