Кристиночке, дорогой

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "math.h"
#include "string"
#include "bits/stdc++.h"

MainWindow::MainWindow(QWidget [id2956970|*parent]) :
 QMainWindow(parent),
 ui(new Ui::MainWindow)
{
 ui->setupUi(this);
}

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


string transformation(int value, int base)
{
    string output;
    while(value > 0)
    {
        char digit = value % base;

        if(digit < 10)
            digit += 48;
        else
            digit += 55;
        output += digit;
        int ost = value % base;
        value /= base;
    }
    reverse(output.begin(), output.end());
    return output;
}

void MainWindow::on_pushButton_Result_clicked()
{
 QString str,bases;
 int input, base;

 str = ui->lineEdit_Decimal->text(); // input number
 bases = ui->lineEdit_Base->text();  // input base to
 input=str.toInt();
 base=bases.toInt();

 QString output;
 output = transformation(input, base);
 ui->label_Binary->setText(output); //output

}