A New Task (Guess)

Task:

We would like to write a program to play a number guessing game with the computer. The computer will "think" of a number from 1 to 100, and give the player six guesses to try to find the number. With each guess, the computer will give the player a hint, telling them if their guess is too high or too low. The player should be given the option of playing the game as many times as they like.

Where do we start?

This time we will take a top down approach to designing the program. We will break the problem down into smaller chunks, or modules, and attack each one, one at a time.

We still begin with the five step process.

1. Understand the problem

What is this program supposed to do?

The problem statement is pretty clear. The program should play this guessing game.

What kind of information is it given? (What is the input?)

The input is the set of player guesses, one at a time, until the player either gets the number, or runs out of guesses.

What kind of results is it to produce? (What is the output?)

The output is a hint after each wrong guess telling the player if their guess is too high or too low.

What formulas or techniques will be needed?

Most of the operation of the game is straightforward - we compare the player's guess with the stored number. One tricky thing we will have to worry about is generating the random number.

2. Do a small example by hand

We can try a small hand example.

• We pick a random number between 1 and 100, say the number is 49.
• We prompt the player to enter a guess, say they enter 12.
• This is their first guess.
• 12 is less than 49, so we hint their guess is too low.
• We prompt again for a guess, say they enter 35. This is their second guess.
• 35 is still less than 49, so we hint their guess is too low again.
• We prompt again for a guess, say they enter 99. This is their third guess.
• 99 is greater than 49, so we hint their guess is too high.
• We continue like that until the player either guesses the number, or they run out of guesses - i.e. get the number wrong on the 6th try. We then tell the player they win or lose.

3. Write an algorithm for solving the problem

Here is where our approach differs from bottom up. Instead of trying to write the algorithm for the entire program, we begin by breaking up the program into modules to handle the details of different aspects of solving the task.

Our modules are: Driver, Pick, and Play.

The algorithms are shown in the Driver Algorithm, the Pick Algorithm, and the Play Algorithm.

4. Translate the algorithm into a programming language (like C)

The code for the modules are

Driver - guess.c - a driver includes a main function

Pick - guess.h

Play - sequence.c and test.c

5. Test the program

Let's run the program in class.