Bad information computing when building a Qt Slog - c++

Question

Hey guys I am trying to make the following slot: The user should input a sequence of numbers in a line edit with spaces between them (for example: 5 10 15 10 2) I want these numbers to be stored into a vector of integers. After they are all read, I want the values of the vector to be changed in the following way - starting from the second element up to the end, every element should be equal to the following: vector[i] = vector[i] - vector[i-1]. Again, this doesn't count for the first one. I will do some more computing, but It would appear that I can't get this done quite right yet.
The layout is the following: a button, a lineEdit and a Label.
This is the header file:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QVector>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
QVector<int> vec;
private slots:
void compute();
};
#endif // MAINWINDOW_H
And the implementation:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QString>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
connect(ui->lineEdit
, SIGNAL(editingFinished()), this, SLOT(compute()));
connect(ui->pushButton
, SIGNAL(pressed()), this, SLOT(compute()));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow :: compute()
{
// Read user input
QString numbers = ui->lineEdit->text();
QString tmp; // create temp string which will be used to store the temp substrings of each int
numbers+=" ";
for(int i = 0; i < numbers.length()-1; i++)
{
if(numbers[i].isDigit())
{
tmp +=numbers[i];
}
else
{
bool ok = true;
int iTime = tmp.toInt(&ok, 10);
vec.push_back((iTime));
tmp="";
}
}
//compute the real vector that we will search the max subarray from
for(int i = 1; i < vec.size(); i++)
{
vec[i] = vec[i] - vec[i-1];
}
int tt = 0;
for(int z = 0; z != vec.size(); z++)
{
tt+= vec[z];
}
ui->label->setText( QString::number(tt));
}
I won't post the main function since it is the standard one when you create a Qt GUI aplication. So, the problem is, the following line: ui->label->setText( QString::number(tt)); always prints zero to the label. I made this program in code blocks, without the Qt GUI libraries and I got it working. I am intrigued where the problem is. Thanks in advance.

Answer 1

for(int z = 0; z != vec.size(); z++)
Should be:
for(int z = 0; z < vec.size(); z++)