A program with Functions

We have learned a lot of concepts so far, and to make sure we are on track, lets write a program that contains all the knowledge in this chapter combined with previous chapters.

This code is called 'Guess the Number'. This is a very simple program to guess the number selected by the computer at random!

# This is a guess the number game.

import random

secretNumber = random.randint(1, 20)

print('I am thinking of a number between 1 and 20.')

# Ask the player to guess 6 times.

for guessesTaken in range(1, 7):
    print('Take a guess.')
    guess = int(input())

    if guess < secretNumber:
        print('Your guess is too low.')
    elif guess > secretNumber:
        print('Your guess is too high.')
    else:
        break    # This condition is the correct guess!

if guess == secretNumber:
    print('Good job! You guessed my number in ' + str(guessesTaken) + ' guesses!')
else:
    print('Nope. The number I was thinking of was ' + str(secretNumber))

Does the program look too scary? Well, let's start with the output:

I am thinking of a number between 1 and 20.
Take a guess.
 1
Your guess is too low.
Take a guess.
 2
Your guess is too low.
Take a guess.
 3
Your guess is too low.
Take a guess.
 4
Your guess is too low.
Take a guess.
 20
Your guess is too high.
Take a guess.
 19
Your guess is too high.
Nope. The number I was thinking of was 12

What we see is that the program only runs a maximum of 6 times! After that it terminates itself. This can be observed from the for guessesTaken in range(1, 7): condition.

Lets try another run:

I am thinking of a number between 1 and 20.
Take a guess.
9
Your guess is too low.
Take a guess.
14
Your guess is too low.
Take a guess.
19
Your guess is too high.
Take a guess.
15
Good job! You guessed my number in 4 guesses!

Here it terminates in 4 tries, after the user figures out the number. These statements take care of the termination, by force or by luck:

if guess == secretNumber:
    print('Good job! You guessed my number in ' + str(guessesTaken) + ' guesses!')
else:
    print('Nope. The number I was thinking of was ' + str(secretNumber))

Now, lets scan the program block by block:

# This is a guess the number game.
import random
secretNumber = random.randint(1, 20)
print('I am thinking of a number between 1 and 20.')

Here, we first import random in order to use the random.randint() function, as learnt in the last units. Once we store the random number inside a variable named secretNumber, we start the game.

for guessesTaken in range(1, 7):
    print('Take a guess.')
    guess = int(input())

    if guess < secretNumber:
        print('Your guess is too low.')
    elif guess > secretNumber:
        print('Your guess is too high.')
    else:
        break    # This condition is the correct guess!

This loop runs 6 times, as the range is 1 to 7. We recall that a range functions runs from the first argument to the second argument, ignoring the latter. This means that the user has 6 tries to figure out the number. We take an input by using guess = int(input()) and stores it in the guess variable.

After this, we check if the guess is greater, smaller or equal to the secretNumber. If it is smaller than the secretNumber, then we print that it's too low. Otherwise, if it is larger than the secretNumber, then we print that it too high. Now, what if they guess the right number? We break the loop.

if guess == secretNumber:
    print('Good job! You guessed my number in ' + str(guessesTaken) + ' guesses!')
else:
    print('Nope. The number I was thinking of was ' + str(secretNumber))

Now, finally moving to the last block. If the guess is equal to the secretNumber, then we print that they did a good job, along with the number of chances it took for them to guess it. Otherwise, we show them the number stored in secretNumber.

With this, we end the chapter on Functions. Let's move on to some questions before diving deeper into advanced concepts!