Page 182 - Learn To Program With Scratch

Stop commands
Let’s say you’re writing a program to find the first integer less than 1,000
that is evenly divisible by 3, 5, and 7. You can write a script that checks
the numbers 999, 998, 997, and so on, one by one, in a loop. You want to
stop the search when you find the number you’re looking for (945 in this
example).
How can you tell Scratch to end the loop and stop the script? You can
use the stop command (from the Control palette) to end active scripts. The
drop-down menu provides the three options shown in Figure 7-6.

or Stage
Stop the script that Stop all scripts in the Stop all scripts in a sprite except the
invoked this block. application. one that invoked this block.

Figure 7-6: Using the stop command in Scratch

The first option immediately terminates the script that calls it. The
second option, on the other hand, stops all running scripts in your appli-
cation; it is equivalent to the red stop icon located at the top of the Stage.
Note that you can’t snap any commands after the stop block when you use
either of these two options.
StopDemo .sb2 The third stop option allows a sprite or the Stage to end all of its scripts
except the one that invoked the stop block. This command is shaped as a
stack block, so you can add blocks below it to execute after it suspends the
sprite’s other scripts. Let’s see this command in action in a simple game,
illustrated in Figure 7-7.

Ball2 Sprite

Player Sprite

Ball1 Sprite

Figure 7-7: In this game, the player moves the witch on the Stage while trying to
avoid the two balls .

160 Chapter 7
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