Page 223 - Learn To Program With Scratch

try it out 8-6
Make the Driver sprite validate the number entered by the user before broadcast-
ing the BinaryToDecimal message to the Bit sprite . You should verify that (1) the
number entered by the user is a binary number (that is, it only contains ones and
zeros) and (2) the length of the input is at most eight digits .

Hangman
Hangman .sb2 In this section, we’ll write a classic Hangman game. Figure 8-23 shows the
game in action.

Helper sprite
(hidden)
Hangman sprite

New sprite

Variable rem

Variables c1 to c6
Driver sprite
(hidden)

Figure 8-23: The user interface for the Hangman game
The program randomly selects a secret six-letter word and shows one
question mark for each letter. The player has eight chances to guess the let-
ters in the word. If the player guesses a letter correctly, the program shows
all occurrences of that letter in the secret word. Otherwise, the program
shows a new part of a hanging figure (the head, body, left arm, and so on).
After eight wrong guesses, the program finishes the figure, and the player
loses the game. If the player guesses the secret word in eight attempts or
fewer, the result is victory. This application has the following four sprites:
Driver This sprite hides itself when the game starts, prompts the
player to enter guesses, and processes the player’s answers. When the
game ends, the sprite shows one of the following two costumes:

Hangman This sprite displays the evolving image of the hangman. It
has a total of nine costumes, each one showing an additional part of
the hangman’s body, as depicted in Figure 8-24.

String Processing 201

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