Guessing Game¶

We are going to create a simple guessing game.

We will choose a random number between 1 and 100
We will ask the user to guess that number
If their guess is too high/low, we tell them that and let them try again
When they succeed, we say “Yay”

Breaking Down the Problem (Pseudocode)¶

What are the steps we are going to take:

# create a random number
# loop until success
    # get user's number as integer
    # compare with the number
        # print out guidance

Code Walk Through¶

Here’s what the final script might look like:

import random
number = random.randint( 1, 100 )

success = False # we haven't yet succeeded
while not success:
    
    guess = raw_input('What is your guess? ')
    guess = int(guess) # guess was a string, now an integer
    
    if guess > number:
        print( "Too high")
    elif guess < number:
        print( "Too low")
    else:
        print( "You rock!" )
    
    success = (guess == number)

Create a Random Number¶

Someone wrote a module that provides functions related to (psuedo)-random numbers
The module is called random
There is a function in it called random.randint()

# load the library of code (module) called random
import random
# random is a module full of functions
# one of which is randint()
# we want to *remember* our random integer for later...
number = random.randint(1,100)

what does all that mean:

random.randint # gets a name *inside* the "random" module
( ) # sends a *message* to that thing
1, 100 # passes two parameters as part of that message
number = # assigns the result of sending the message to a variable

we are going to define our own functions in our next game: Trivia Game

Exercise: Setup the Game Script¶

We are going to create a script that will become our game.

In Idle or PyScripter create a new file (our script)
- File | New Window
Save the empty script into your home directory (H:)
- File | Save As

In the script type:

import random
number = random.randint(1,100)
print(number)

Save the script again
Run the script with Idle <F5> or PyScripter <F9>

Ask for a Number¶

How do we ask the user for input?
Recall that the function for this is called input()
It takes an argument that is the prompt you want to present to the user and returns the text (string) they typed

guess = input('What is your guess? ')
# ick, guess is a str, we want an int
guess = int(guess)

Note

If you are using Python 2.x you need to use raw_input() instead of input().

Exercise: Ask for a Number¶

Modify your game to give the user one chance to guess the number
Remember to convert their input to an integer
print the guess and the number (again, to let us see if it is working)

Review: Ask for a Number¶

import random
number = random.randint( 1, 100 )

guess = raw_input('What is your guess? ')
guess = int(guess)

print( number,  guess )

Until the User Succeeds¶

What is success in this game? Success is when the user’s guess is equal to the number.

success = (guess == number)

We want to keep asking until the user succeeds:

while not success:
    ...
    success = (guess==number)

>>> n = 3
>>> while n > 0:
...     print(n)
...     n = n-1
...
3
2
1

Exercise: Loop Until Success¶

Modify your script so that the user is asked to guess until they succeed

Note

Pretty hard, eh? You can stop before you guess the number by hitting <ctrl-c> on the keyboard to interrupt the script.

Review: Loop Until Success¶

import random
number = random.randint( 1, 100 )

success = False
while not success:

    guess = raw_input('What is your guess? ')
    guess = int(guess)
    
    success = (guess == number)

Give Guidance and Congratulations¶

We want to do something if one of these two cases is True:
- Guess is too high (> number)
- Guess is too low (< number)
This sounds like an if statement

if <test>:
    do_first_thing()
elif <othertest>:
    do_other_thing()
else:
    do_thing_when_other_tests_false()

Exercise: Give Guidance¶

Modify your game to tell the user when they are too high or too low

Review: Give Guidance¶

import random
number = random.randint( 1, 100 )

success = False # we haven't yet succeeded
while not success:
    
    guess = raw_input('What is your guess? ')
    guess = int(guess) # guess was a string, now an integer
    
    if guess > number:
        print( "Too high")
    elif guess < number:
        print( "Too low")
    else:
        print( "You rock!" )
    
    success = (guess == number)

Extra Exercises¶

Modify your script to track the number of guesses and report to the user
Figure out the best strategy to win the game