Functions and the Guessing Game

Step 1: Your own functions

You have already used functions like print() and input(). Now you will write your own. A function is a named block of code that you can run whenever you want.

def say_hello():
    print("Hello!")
    print("Welcome to Python.")

say_hello()
say_hello()

Hello!
Welcome to Python.
Hello!
Welcome to Python.

• def starts the definition, followed by a name and ().
• The lines inside are indented.
• Writing the function does nothing by itself. It runs only when you call it with say_hello().

Step 2: Parameters

A function becomes more useful when you can give it information. Names inside the parentheses are parameters.

def greet(name):
    print("Hello, " + name + "!")

greet("Amara")
greet("Jabari")

Hello, Amara!
Hello, Jabari!

Step 3: Returning a value

print() shows something to the user. return sends a value back to the code that called the function, so it can be stored or used in math.

def double(n):
    return n * 2

result = double(21)
print(result)
print(double(5) + 1)

42
11

A function can return True or False too, which makes it a perfect helper for if statements:

def is_even(number):
    return number % 2 == 0

if is_even(10):
    print("10 is even")

10 is even

Step 4: Random numbers

Python comes with ready-made toolboxes called modules. To use one, import it. The random module can pick numbers by chance.

import random

roll = random.randint(1, 6)
print("You rolled a", roll)

You rolled a 4

Your number will be different each time you run it. random.randint(1, 6) includes both 1 and 6.

Step 5: Plan the guessing game

Before coding, plan it in plain language:

1. The computer picks a secret number.
2. Ask the player for a guess.
3. If the guess is too high, say so. If too low, say so.
4. Repeat until the guess is right.
5. Tell the player how many guesses it took.

Here is a skeleton. Your job in the project is to fill in the gaps.

import random

def get_guess():
    return int(input("Your guess: "))

secret = random.randint(1, 100)
tries = 0

while True:
    guess = get_guess()
    tries += 1
    if guess > secret:
        print("Too high!")
    elif guess < secret:
        print("Too low!")
    else:
        print(f"You got it in {tries} guesses!")
        break

Your guess: 50
Too high!
Your guess: 25
Too low!
Your guess: 37
You got it in 3 guesses!

Step 6: What you can do now

Look at the skeleton. It uses almost everything from this workshop:

• variables (secret, tries)
• decisions (if, elif, else)
• loops (while True and break)
• functions (get_guess)
• modules (random)

You built a real game. Next you can add a play-again option, limit the number of guesses, or make the game smarter about hints. That is how programmers work: start with something small that works, then keep improving it.