Page 173 - Learn To Program With Scratch

try it out 6-4

Open the application and run it . Drag the two points to different locations on the
Stage and check the displayed equation . To enhance this application, try adding
a script to move Tutor sprite out of the way if it overlaps with the coordinates dis-
played by the Point1 and Point2 sprites .

Other Applications

GuessMy Now let’s discuss some games you’ll find in the extra resources for this book
Number .sb2 (download the extra resources from http://nostarch.com/learnscratch/). The
supplementary material contains two classic games that you can explore on
your own. The first is a “guess my number” game. The application secretly
selects an integer at random between 1 and 100 and prompts the player to
guess that number. The application then tells the player whether the guess
was higher or lower than the secret number by displaying “too high” or “too
low,” respectively. The player has six chances to guess the secret number.
A correct guess wins the game; otherwise, it’s a loss.
RockPaper .sb2 The second game allows the user to play Rock, Paper, Scissors against
the computer. The player makes a selection by clicking one of three but-
tons that represent rock, paper, or scissors. The computer makes a random
selection. The winner is selected according to the following rules: Paper
beats (wraps) rock, rock beats (breaks) scissors, and scissors beat (cut)
paper.

Summary

In this chapter, you learned about the comparison operators in Scratch and
used them to compare numbers, characters, and strings. After that, you
learned about the if and if/else blocks and used them to make decisions
and control actions in several programs. You also learned how to use nested
if and if/else blocks for testing multiple conditions and applied this tech-
nique to develop a menu-driven application. You also learned about logical
operators as an alternative, and more concise, way to test multiple condi-
tions. Finally, you explored several complete applications that demonstrated
decision-making structures in action.
The next chapter will take you deeper into the Control palette, showing
you the various repetition structures available in Scratch and teaching you
how to use them to write even more powerful programs.

Making Decisions 151

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