Learn Python The Hard Way

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• Preface
• Introduction: The Hard Way Is Easier
• Exercise 0: The Setup
• Exercise 1: A Good First Program
• Exercise 2: Comments And Pound Characters
• Exercise 3: Numbers And Math
• Exercise 4: Variables And Names
• Exercise 5: More Variables And Printing
• Exercise 6: Strings And Text
• Exercise 7: More Printing
• Exercise 8: Printing, Printing
• Exercise 9: Printing, Printing, Printing
• Exercise 10: What Was That?
• Exercise 11: Asking Questions
• Exercise 12: Prompting Peopley
• Exercise 13: Parameters, Unpacking, Variables
• Exercise 14: Prompting And Passing
• Exercise 15: Reading Files
• Exercise 16: Reading And Writing Files
• Exercise 17: More Files
• Exercise 18: Names, Variables, Code, Functions
• Exercise 19: Functions And Variables
• Exercise 20: Functions And Files
• Exercise 21: Functions Can Return Something
• Exercise 22: What Do You Know So Far?
• Exercise 23: Read Some Code
• Exercise 24: More Practice
• Exercise 25: Even More Practice
• Exercise 26: Congratulations, Take A Test!
• Exercise 27: Memorizing Logic
• Exercise 28: Boolean Practice
• Exercise 29: What If
• Exercise 30: Else And If
• Exercise 31: Making Decisions
• Exercise 32: Loops And Lists
• Exercise 33: While Loops
• Exercise 34: Accessing Elements Of Lists
• Exercise 35: Branches and Functions
• Exercise 36: Designing and Debugging
• Exercise 37: Symbol Review
• Exercise 38: Doing Things To Lists
• Exercise 39: Dictionaries, Oh Lovely Dictionaries
• Exercise 40: Modules, Classes, And Objects
• Exercise 41: Learning To Speak Object Oriented
• Exercise 42: Is-A, Has-A, Objects, and Classes
• Exercise 43: Gothons From Planet Percal #25
• Exercise 44: Inheritance Vs. Composition
• Exercise 45: You Make A Game
• Exercise 46: A Project Skeleton
• Exercise 47: Automated Testing
• Exercise 48: Advanced User Input
• Exercise 49: Making Sentences
• Exercise 50: Your First Website
• Exercise 51: Getting Input From A Browser
• Exercise 52: The Start Of Your Web Game
• Advice From An Old Programmer
• Next Steps
• Appendix A: Command Line Crash Course

Preface

My book gives you your"programming black belt".

Introduction: The Hard Way Is Easier

Three most essential skills that a beginning programmer needs to know: reading and writing, attention to detail, and spotting differences.

Exercise 0: The Setup

Get your computer to run Python

Exercise 1: A Good First Program

print("Hello World!")
print ("Hello Again")
print ("I like typing this.")
print ("This is fun.")
print ('Yay! Printing.')
print ("I'd much rather you 'not'.")
print ('I "said" do not touch this.')

Note

An "octothorpe" is also called a "pound", "hash", "mesh", or any number of names. Pick the one that makes you chill out.

Warning

If you are from another country, and you get errors about ASCII encodings, then put this at the top of your Python scripts:

# -*- coding: utf-8 -*-

It will fix them so that you can use Unicode UTF-8 in your scripts without a problem.

Exercise 2: Comments and Pound Characters

# A comment, this is so you can read your program later.
# Anything after the # is ignored by python.

print("I could have code like this.") # and the comment after is ignored

# You can also use a comment to "disable" or comment out a piece of code:
# print "This won't run."

print("This will run.")

Exercise 3: Numbers and Math

Names:

• +plus
• -minus
• /slash
• *asterisk
• %percent
• <less-than
• >greater-than
• <=less-than-equal
• >=greater-than-equal

print("I will now count my chickens:")

print("Hens", 25 + 30 / 6)
print("Roosters", 100 - 25 * 3 % 4)

print("Now I will count the eggs:")

print(3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6)

print("Is it true that 3 + 2 < 5 - 7?")

print(3 + 2 < 5 - 7)

print( "What is 3 + 2?", 3 + 2)
print("What is 5 - 7?", 5 - 7)

print("Oh, that's why it's False.")

print("How about some more.")

print("Is it greater?", 5 > -2)
print("Is it greater or equal?", 5 >= -2)
print("Is it less or equal?", 5 <= -2)

Exercise 4: Variables And Names

cars = 100
space_in_a_car = 4.0
drivers = 30
passengers = 90
cars_not_driven = cars - drivers
cars_driven = drivers
carpool_capacity = cars_driven * space_in_a_car
average_passengers_per_car = passengers / cars_driven


print ("There are", cars, "cars available.")
print ("There are only", drivers, "drivers available.")
print ("There will be", cars_not_driven, "empty cars today.")
print ("We can transport", carpool_capacity, "people today.")
print ("We have", passengers, "to carpool today.")
print ("We need to put about", average_passengers_per_car, "in each car.")

Note

The_inspace_in_a_caris called anunderscore character. Find out how to type it if you do not already know. We use this character a lot to put an imaginary space between words in variable names.

Exercise 5: More Variables and Printing

my_name = 'Zed A. Shaw'
my_age = 35 # not a lie
my_height = 74 # inches
my_weight = 180 # lbs
my_eyes = 'Blue'
my_teeth = 'White'
my_hair = 'Brown'

print ("Let's talk about %s." % my_name)
print ("Actually that's not too heavy.")
print ("He's got %s eyes and %s hair." % (my_eyes, my_hair))
print ("His teeth are usually %s depending on the coffee." % my_teeth)

# this line is tricky, try to get it exactly right
print ("If I add %d, %d, and %d I get %d." % (my_age, my_height, my_weight, my_age + my_height + my_weight))

Exercise 6: Strings And Text

types_of_people = 10
x = f"There are {types_of_people} types of people"

binary = 'binary'
do_not = "don't"
y=f"Those who know {binary} and those who {do_not}"

print(x)
print(y)

print(f"I sid: {x}")
print(f"I also said: '{y}'")

hilarious = False
joke_evaluation = "Isn't that joke so funny?!{}"
print(joke_evaluation.format(hilarious))

w = "This is the left side of..."
e = "a string with a right side"

print(w + e)

Exercise 7: More Printing

print("Mary had a little lamb.")
print("Its fleece was white as {}.".format('snow'))
print("And everywhere that Mary went.")
print("." * 10) # what'd that do?
end1 = "C"
end2 = "h"
end3 = "e"
end4 = "e"
end5 = "s"
end6 = "e"
end7 = "B"
end8 = "u"
end9 = "r"
end10 = "g"
end11 = "e"
end12 = "r"
# watch end = ' ' at the end. try removing it to see what happens
print(end1 + end2 + end3 + end4 + end5 + end6, end=' ')
print(end7 + end8 + end9 + end10 + end11 + end12, end='')
print(end1)

Exercise 8:Printing,Printing

formatter = "{} {} {} {}"
print(formatter.format(1, 2, 3, 4))
print(formatter.format("one", "two", "three", "four"))
print(formatter.format(True, False, False, True))
print(formatter.format(formatter, formatter, formatter, formatter))
print(formatter.format("Try your","Own text here","Maybe a poem","Or a song about fear"))

Exercise 9:Printing,Printing,Printing

# Here's some new strange stuff, remember type it exactly
days = "Mon Tue Wed Thu Fri Sat Sun"
months = "Jan\nFeb\nMar\nApr\nMay\nJun\nJul\nAug"
print("Here are the days: ", days)
print("Here are the months: ", months)
print("""There's something going on here.
With the three double-quotes.
We'll be able to type as much as we like.
Even 4 lines if we want, or 5, or 6. 14
""")

Exercise 10: What Was That?

tabby_cat = "\tI'm tabbed in."
persian_cat = "I'm split\non a line."
backslash_cat = "I'm \\ a \\ cat."
fat_cat = """
I'll do a list:
\t* Cat food
\t* Fishies
\t* Catnip\n\t* Grass
"""
print(tabby_cat)
print(persian_cat)
print(backslash_cat)
print(fat_cat)
print("\a"+"\n"+"\b"+"\n"+"\f"+"\n"+"\r"+"\n"+"\t"+"\n"+"\v")

Exercise 11: Asking Questions

print("How old are you?", end=' ')
age = input()
print("How tall are you?", end=' ')
height = input()
print("How much do you weigh?", end=' ')
weight = input()

print(f"So, you're {age} old, {height} tall and {weight} heavy.")

Exercise 12: Prompting People

age = input("How old are you? ")
height = input("How tall are you? ")
weight = input("How much do you weigh? ")

print(f"So, you're {age} old, {height} tall and {weight} heavy.")

Exercise 13: Parameters, Unpacking, Variables

from sys import argv
# read the WYSS section for how to run this

script, first, second, third = argv

print("The script is called:", script)
print("Your first variable is：", first)
print("Your second variable is:", second)
print("Your third variable is:", third)