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# Qt Tutorial 6 - Building Blocks Galore!

This example shows how to encapsulate two widgets into a new component and how easy it is to use many widgets. For the first time, we use a custom widget as a child widget. Missing snippet: tutorials/tutorial/t6/main.cpp.
Missing snippet: tutorials/tutorial/t6/main.cpp.
Missing snippet: tutorials/tutorial/t6/main.cpp.
Missing snippet: tutorials/tutorial/t6/main.cpp.
Missing snippet: tutorials/tutorial/t6/main.cpp.

## Line by Line Walkthrough

Missing snippet: tutorials/tutorial/t6/main.cpp. The `LCDRange` widget is a widget without any API. It just has a constructor. This sort of widget is not very useful, so we'll add some API later. Missing snippet: tutorials/tutorial/t6/main.cpp. This is lifted straight from the `MyWidget` constructor in Chapter 5. The only differences are that the Quit button is left out and the class is renamed. Missing snippet: tutorials/tutorial/t6/main.cpp. `MyWidget`, too, contains no API except a constructor. Missing snippet: tutorials/tutorial/t6/main.cpp. The push button that used to be in what is now `LCDRange` has been separated so that we can have one Quit button and many `LCDRange` objects. Missing snippet: tutorials/tutorial/t6/main.cpp. We create a QWidget with a QGridLayout that will contain three columns.

The QGridLayout automatically arranges its widgets in rows and columns; you can specify the row and column numbers when adding widgets to the layout, and QGridLayout will fit them into the grid. Missing snippet: tutorials/tutorial/t6/main.cpp. Missing snippet: tutorials/tutorial/t6/main.cpp. Missing snippet: tutorials/tutorial/t6/main.cpp. Missing snippet: tutorials/tutorial/t6/main.cpp. Missing snippet: tutorials/tutorial/t6/main.cpp. We create nine `LCDRange` widgets, all of which are children of the grid object, and we arrange them in three rows and three columns. Missing snippet: tutorials/tutorial/t6/main.cpp. Finally, we add the Quit button and the grid layout containing `LCDRange` widgets, to the main layout. The QWidget::addLayout() function is similar to the QWidget::addWidget() function, making the given layout a child of the main layout.

That's all.

## Running the Application

This program shows how easy it is to use many widgets at a time. Each one behaves like the slider and LCD number in the previous chapter. Again, the difference lies in the implementation.

## Exercises

Initialize each slider with a different/random value on startup.