author: Scott Morgan summary: This codelab focusses on creating a simple guessing game in Python. id: guess-the-number categories: python-programming environments: Web status: Hidden feedback link: https://github.com/Scott3142/python-programming analytics account: UA-49751789-4
Duration: 00:30:00
In this short project, we’ll be exploring how to create a guess the random number game. We’ll start with guessing a number that the computer has chosen and then move on to having the computer guess a number that the user has chosen. This example should give you some practise working with loops and conditional statements and revise how to take and process user input.
It’s always useful when starting out creating a program or an app to write down or draw the flow of the program, sometimes in something called pseudocode. We won’t worry too much about the finer points of psuedocode here but we’ll just sketch out the flow of what we want the program to do below:
computer chooses random number
loop until we get it right
computer asks us to guess
if the guess is right
computer says yes
otherwise
computer says try again
It looks like there are four key components to this program that we’ll have to address in our code.
You can find the relevant informtion for each of these points in Part 1 and Part 2 of the course material.
There are two natural places where we could add improvements to this program to make life a little bit easier for the guesser. At the moment, there is no limit on the random number that the computer guesses and there is no way of knowing if we were close or not with our guess. We could end up guessing forever and not getting the answer right! This doesn’t make the game much fun, so let’s look at the code again and see how we can change it.
We can change the first line so that a range is specified for the random number choice. You could even implement a levelling system here so that the range gets larger as users guess correctly more and more times.
computer chooses random number between 1 and 10
We can edit the conditional statements in the loop to deal with the second problem by adding print statements which tell us if our guess was too high or too low. This way, we’re always getting closer to the answer on every guess.
if the number is too low
computer says higher
if the number is too high
computer says lower
In the next exercise you will implement this program yourself in Python.
Duration: 00:30:00
This time around we’ll be thinking of the number as a user and asking the computer to try and guess it. We’ll follow exactly the same rules as before, but there are some added complexities in this version that we’ll see as we go through it.
Let’s look at the structure of the program, simply adapted from the previous version:
user thinks of random number (no coding here!)
loop until the computer gets it right
computer guesses random number
if the guess is right
user inputs yes
otherwise
if the number is too low
user inputs higher
if the number is too high
user inputs lower
There are some potential issues with this implementation. When it was the human guessing, we can be pretty confident that we wouldn’t guess the same incorrect number twice, and that we understand what the terms higher and lower mean. This is not necessarily true of the computer as this algorithm stands, so let’s take a look at how we can change it.
We need to fix two things:
In the following exercise, you will implement this program in Python. Can you fix the two points described above?
Hint: You may want to use a list to store the guesses.
Duration: 00:30:00
The final part of this exercise will explore how we can build the guess a number functionality into a web app using Python’s Flask library. We won’t worry about the mechanisms of creating the pages and we won’t bother with any HTML, CSS or JavaScript. The exercise files will contain all the relevant files you need to get going and just implement the Python part.
The most basic task we can achieve in Flask is the age-old “Hello World!” application. Here’s how it looks:
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello_world():
return 'Hello, World!'
if __name__ == '__main__':
app.run()
This code outputs “Hello, World!” in a web browser on your computer’s localhost port 5000 (i.e. at http://localhost:5000) when run with the python3 app.py command and the Flask library installed.
You can set up a virtual environment and install flask using the following commands in a terminal:
user@host:~$ virtualenv flask_env
user@host:~$ source flask_env/bin/activate
user@host:~$ pip install flask
user@host:~$ python3 app.py
Once you have done that, clone the exercise repo below and follow the instructions in the README.