#include <QApplication>
#include <QDesktopWidget>
#include <QTextEdit>
 
 
class Absolute : public QWidget
{
 public:
     Absolute(QWidget *parent = 0);
};
 
 
Absolute::Absolute(QWidget *parent)
    : QWidget(parent)
{
  QTextEdit *edit = new QTextEdit(this);
  edit->setGeometry(5, 5, 200, 150);
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  Absolute window;
 
  window.setWindowTitle("Absolute");
  window.show();
 
  return app.exec();
}
 QTextEdit *edit = new QTextEdit(this);
 edit->setGeometry(5, 5, 200, 150);

verticalbox.h
 
#ifndef VERTICALBOX_H
#define VERTICALBOX_H
 
#include <QWidget>
 
class VerticalBox : public QWidget
{
  public:
    VerticalBox(QWidget *parent = 0);
 
};
 
#endif
 

 
#include "verticalbox.h"
#include <QVBoxLayout>
#include <QPushButton>
 
VerticalBox::VerticalBox(QWidget *parent)
    : QWidget(parent)
{
 
  QVBoxLayout *vbox = new QVBoxLayout(this);
  vbox->setSpacing(1);
 
  QPushButton *settings = new QPushButton("Settings", this);
  settings->setSizePolicy(QSizePolicy::Expanding, 
      QSizePolicy::Expanding);
  QPushButton *accounts = new QPushButton("Accounts", this);
  accounts->setSizePolicy(QSizePolicy::Expanding, 
      QSizePolicy::Expanding);
  QPushButton *loans = new QPushButton("Loans", this);
  loans->setSizePolicy(QSizePolicy::Expanding, 
      QSizePolicy::Expanding);
  QPushButton *cash = new QPushButton("Cash", this);
  cash->setSizePolicy(QSizePolicy::Expanding, 
      QSizePolicy::Expanding);
  QPushButton *debts = new QPushButton("Debts", this);
  debts->setSizePolicy(QSizePolicy::Expanding, 
      QSizePolicy::Expanding);
 
  vbox->addWidget(settings);
  vbox->addWidget(accounts);
  vbox->addWidget(loans);
  vbox->addWidget(cash);
  vbox->addWidget(debts);
 
  setLayout(vbox);
}

 
 QVBoxLayout *vbox = new QVBoxLayout(this);
 vbox->setSpacing(1);

QPushButton *settings = new QPushButton("Settings", this);
 settings->setSizePolicy(QSizePolicy::Expanding, 
     QSizePolicy::Expanding);

 vbox->addWidget(settings);
 vbox->addWidget(accounts);
 vbox->addWidget(loans);
 vbox->addWidget(cash);
 vbox->addWidget(debts);

 setLayout(vbox);

 
#include "verticalbox.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
 
  int WIDTH = 200;
  int HEIGHT = 250;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - WIDTH) / 2;
  y = (screenHeight - HEIGHT) / 2;
 
  widget.setGeometry(x, y, WIDTH, HEIGHT);
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv); 
 
  VerticalBox window;
 
  window.setWindowTitle("VerticalBox");
  window.show();
  center(window);
 
  return app.exec();
}
 

 
#ifndef BUTTONS_H
#define BUTTONS_H
 
#include <QWidget>
#include <QPushButton>
 
class Buttons : public QWidget
{
  public:
    Buttons(QWidget *parent = 0);
 
  private:
    QPushButton *ok;
    QPushButton *apply;
 
};
 
#endif

 
#include "buttons.h"
#include <QVBoxLayout>
#include <QHBoxLayout>
 
 
Buttons::Buttons(QWidget *parent)
    : QWidget(parent)
{
 
  QVBoxLayout *vbox = new QVBoxLayout(this);
  QHBoxLayout *hbox = new QHBoxLayout();
 
  ok = new QPushButton("OK", this);
  apply = new QPushButton("Apply", this);
 
  hbox->addWidget(ok, 1, Qt::AlignRight);
  hbox->addWidget(apply, 0, Qt::AlignRight);
 
  vbox->addStretch(1);
  vbox->addLayout(hbox);
 
}

QVBoxLayout *vbox = new QVBoxLayout(this); 
 QHBoxLayout *hbox = new QHBoxLayout();

ok = new QPushButton("OK", this);
 apply = new QPushButton("Apply", this

hbox->addWidget(ok, 1, Qt::AlignRight);
 hbox->addWidget(apply, 0, Qt::AlignRight);

 
 vbox->addStretch(1);
 vbox->addLayout(hbox);

 
#include "buttons.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
 
  int WIDTH = 290;
  int HEIGHT = 170;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - WIDTH) / 2;
  y = (screenHeight - HEIGHT) / 2;
 
  widget.setGeometry(x, y, WIDTH, HEIGHT);
 
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);  
 
  Buttons window;
 
  window.setWindowTitle("Buttons");
  window.show();
  center(window);
 
  return app.exec();
}

 
#ifndef LAYOUTS_H
#define LAYOUTS_H
 
#include <QWidget>
 
class Layouts : public QWidget
{
  public:
    Layouts(QWidget *parent = 0);
 
};
 
#endif

 
#include "layouts.h"
#include <QVBoxLayout>
#include <QPushButton>
#include <QListWidget>
 
Layouts::Layouts(QWidget *parent)
    : QWidget(parent)
{
 
  QVBoxLayout *vbox = new QVBoxLayout();
 
  // must add it to another layout.
  QHBoxLayout *hbox = new QHBoxLayout(this);
 
  QListWidget *lw = new QListWidget(this);
  lw->addItem("The Omen"); 
  lw->addItem("The Exorcist");
  lw->addItem("Notes on a scandal");
  lw->addItem("Fargo");
  lw->addItem("Capote");
 
  QPushButton *add = new QPushButton("Add", this);
  QPushButton *rename = new QPushButton("Rename", this);
  QPushButton *remove = new QPushButton("Remove", this);
  QPushButton *removeall = new QPushButton("Remove All", this);
 
  vbox->setSpacing(3);
  vbox->addStretch(1);
  vbox->addWidget(add);
  vbox->addWidget(rename);
  vbox->addWidget(remove);
  vbox->addWidget(removeall);
  vbox->addStretch(1);
 
  hbox->addWidget(lw);
  hbox->addSpacing(15);
  hbox->addLayout(vbox);
 
  setLayout(hbox);
}

 
 QVBoxLayout *vbox = new QVBoxLayout();

QHBoxLayout *hbox = new QHBoxLayout(this);

QListWidget *lw = new QListWidget(this);
 lw->addItem("The Omen"); 
 lw->addItem("The Exorcist");
 lw->addItem("Notes on a scandal");
 lw->addItem("Fargo");
 lw->addItem("Capote");

 
 QPushButton *add = new QPushButton("Add", this);
 QPushButton *rename = new QPushButton("Rename", this);
 QPushButton *remove = new QPushButton("Remove", this);
 QPushButton *removeall = new QPushButton("Remove All", this);

vbox->setSpacing(3);
 vbox->addStretch(1);
 vbox->addWidget(add);
 vbox->addWidget(rename);
 vbox->addWidget(remove);
 vbox->addWidget(removeall);
 vbox->addStretch(1);

hbox->addWidget(lw);
 hbox->addSpacing(15);
 hbox->addLayout(vbox);

 
#include "layouts.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);  
 
  Layouts window;
 
  window.setWindowTitle("Layouts");
  window.show();
  center(window);
 
  return app.exec();
}
 
 

 
#ifndef CALCULATOR_H
#define CALCULATOR_H
 
#include <QWidget>
#include <QPushButton>
 
class Calculator : public QWidget
{
  public:
    Calculator(QWidget *parent = 0);
 
};
 
#endif

 
#include "calculator.h"
#include <QGridLayout>
 
 
Calculator::Calculator(QWidget *parent)
    : QWidget(parent)
{
 
  QGridLayout *grid = new QGridLayout(this);
  grid->setSpacing(2);
 
  char *values[16] = { "7", "8", "9", "/", 
    "4", "5", "6", "*",
    "1", "2", "3", "-",
    "0", ".", "=", "+"
  };
 
  int pos = 0;
 
  for (int i=0; i<4; i++) {
    for (int j=0; j<4; j++) {
      QPushButton *btn = new QPushButton(values[pos], this);
      btn->setFixedSize(40, 40);
      grid->addWidget(btn, i, j);
      pos++;
    }
  }
 
  setLayout(grid);
 
}

QGridLayout *grid = new QGridLayout(this);
 grid->setSpacing(2);

char *values[16] = { "7", "8", "9", "/", 
   "4", "5", "6", "*",
   "1", "2", "3", "-",
   "0", ".", "=", "+"
 };

 
 for (int i=0; i<4; i++) {
   for (int j=0; j<4; j++) {
     QPushButton *btn = new QPushButton(values[pos], this);
     btn->setFixedSize(40, 40);
     grid->addWidget(btn, i, j);
     pos++;
   }
 }

#include "calculator.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
 
}
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv); 
 
  Calculator window;
 
  window.setWindowTitle("Calculator");
  window.show();
  center(window);
 
  return app.exec();
}

 
#ifndef KARENINA_H
#define KARENINA_H
 
#include <QWidget>
 
class Karenina : public QWidget
{
  public:
    Karenina(QWidget *parent = 0);
 
};
 
#endif

karenina.cpp
 
#include "karenina.h"
#include <QGridLayout>
#include <QLabel>
#include <QLineEdit>
#include <QTextEdit>
 
 
Karenina::Karenina(QWidget *parent)
    : QWidget(parent)
{
 
  QGridLayout *grid = new QGridLayout(this);
  grid->setSpacing(20);
 
  QLabel *title = new QLabel("Title", this);
  grid->addWidget(title, 0, 0, 1, 1);
 
  QLineEdit *edt1 = new QLineEdit(this);
  grid->addWidget(edt1, 0, 1, 1, 1);
 
  QLabel *author = new QLabel("Author", this);
  grid->addWidget(author, 1, 0, 1, 1);
 
  QLineEdit *edt2 = new QLineEdit(this);
  grid->addWidget(edt2, 1, 1, 1, 1);
 
  QLabel *review = new QLabel("Review", this);
  grid->addWidget(review, 2, 0, 1, 1);
 
  QTextEdit *te = new QTextEdit(this);
  grid->addWidget(te, 2, 1, 3, 1);
 
  setLayout(grid);
 
}

QGridLayout *grid = new QGridLayout(this);
 grid->setSpacing(20);

QLabel *title = new QLabel("Title", this);
 grid->addWidget(title, 0, 0, 1, 1);

 
#include "karenina.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
 
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);  
 
  Karenina window;
 
  window.setWindowTitle("Anna Karenina");
  window.show();
  center(window);
 
  return app.exec();
}