CS102B - Lesson 11

What is Python?

• Interpretative language
• Emphasizes code readability
• Dynamic type system (no explicit types)
• Easier to write; good for prototyping
• Slower than C/C++!

First Python Program

print("Game Over")

• Note that there are no semicolons!

if, elif, else

temp = 50 # in F
freezing = 32
boiling = 212

if temp <= freezing:
    print("I'm freezing!")
elif temp >= boiling:
    print("I'm boiling!")
else:
    print("I'm somewhere in between")

• No types for variables
• Note the indentation; it's required!
• You need a colon for conditionals

While Loops

# Three Year-Old Simulator

print("\t Welcome to the 'Three-Year-Old Simulator'\n")
print("This program simulates a conversation with a three-year-old child.")
print("Try to stop the madness.\n")

response = ""
while response != "Because.":
    response = input("Why?\n")

print("Oh. Okay.")

input("\n\nPress the enter key to exit.")

For Loops

print("Counting!")

for i in range(10):
    print(i, end=" ") # end makes print not end in a \n

print("\n\nCounting by fives:")
for i in range(0, 50, 5):
    print(i, end=" ")

print("\n\nCounting backwards:")
for i in range(10, 0, -1):
    print(i, end=" ")

• The final number gets excluded!

Arrays

word = "Python is awesome!"

print(word[0:6]) # excludes last

print(word[-5])

for i in word:
    print(i, end=" ")

List

# Create a list with some items and display them

inventory = ["sword", "armor", "shield", "potion"]
print("Your items:")
for item in inventory:
    print(item)

Dictionary

Hangman Game

# Hangman Game
#
# The classic game of Hangman.  The computer picks a random word
# and the player wrong to guess it, one letter at a time.  If the player
# can't guess the word in time, the little stick figure gets hanged.

# imports
import random

# constants
HANGMAN = (
"""
 ------
 |    |
 |
 |
 |
 |
 |
 |
 |
----------
""",
"""
 ------
 |    |
 |    O
 |
 |
 |
 |
 |
 |
----------
""",
"""
 ------
 |    |
 |    O
 |   -+-
 | 
 |   
 |   
 |   
 |   
----------
""",
"""
 ------
 |    |
 |    O
 |  /-+-
 |   
 |   
 |   
 |   
 |   
----------
""",
"""
 ------
 |    |
 |    O
 |  /-+-/
 |   
 |   
 |   
 |   
 |   
----------
""",
"""
 ------
 |    |
 |    O
 |  /-+-/
 |    |
 |   
 |   
 |   
 |   
----------
""",
"""
 ------
 |    |
 |    O
 |  /-+-/
 |    |
 |    |
 |   | 
 |   | 
 |   
----------
""",
"""
 ------
 |    |
 |    O
 |  /-+-/
 |    |
 |    |
 |   | |
 |   | |
 |  
----------
""")

MAX_WRONG = len(HANGMAN) - 1
WORDS = ("OVERUSED", "CLAM", "GUAM", "TAFFETA", "PYTHON")

# initialize variables
word = random.choice(WORDS)   # the word to be guessed
so_far = "-" * len(word)      # one dash for each letter in word to be guessed
wrong = 0                     # number of wrong guesses player has made
used = []                     # letters already guessed


print("Welcome to Hangman.  Good luck!")

while wrong < MAX_WRONG and so_far != word:
    print(HANGMAN[wrong])
    print("\nYou've used the following letters:\n", used)
    print("\nSo far, the word is:\n", so_far)

    guess = input("\n\nEnter your guess: ")
    guess = guess.upper()

    while guess in used:
        print("You've already guessed the letter", guess)
        guess = input("Enter your guess: ")
        guess = guess.upper()

    used.append(guess)

    if guess in word:
        print("\nYes!", guess, "is in the word!")

        # create a new so_far to include guess
        new = ""
        for i in range(len(word)):
            if guess == word[i]:
                new += guess
            else:
                new += so_far[i]              
        so_far = new

    else:
        print("\nSorry,", guess, "isn't in the word.")
        wrong += 1

if wrong == MAX_WRONG:
    print(HANGMAN[wrong])
    print("\nYou've been hanged!")
else:
    print("\nYou guessed it!")

print("\nThe word was", word)

input("\n\nPress the enter key to exit.")