Raspberry Pi A, Руководство пользователя, Страница: 175 / 314

C H A P T E R 1 1
A N I N T R O D U C T I O N T O S C R A T C H
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Example 1: Hello World
When learning a new programming language, it’s traditional to start with a very basic pro-
gram: one that displays a single line of text. This is typically referred to as a Hello World
program, and it’s the first step towards learning how to create your own programs.
Unlike a traditional programming language, Scratch doesn’t expect the user to memorise the
names of instructions like
print
or
inkey$
. Instead, almost everything is done by dragging
and dropping blocks of code and arranging them into a logical pattern.
To begin, load Scratch by double-clicking its icon on the desktop or clicking on its entry in
the Programming menu. After a few seconds, the main Scratch interface will appear (see
Figure 11-1). If it’s off-centre or small, click the Maximise button—the middle of the three
window control buttons on the right side of the top title bar—to fill the screen.
Figure 11-1:
The main
Scratch
interface, shown
running on the
Raspberry Pi
The Scratch interface is split into multiple panes. At the left is the block palette , which holds all
the different code blocks you can use to create a program. A list of objects in the program,
known as
sprites , appears at the bottom-right along with a control for the stage on which the
sprites appear. The stage itself is at the top-right of the window, which is where you will see the
program running. Finally, the middle of the window is where the program itself is constructed.