Last updated: Monday 27th February 2023, 14:05 PT, AD
# python3programs.html
# anne.dawson@gmail.com
# All Python resources by Dr Anne Dawson are here:
# https://www.annedawson.net/Resources165.html#N13
# Please Note: lines starting with a # are comments
# and are ignored by the Python interpreter...
# See: https://www.annedawson.net/PythonComments.txt
# for important information about comments.
# Any of the example programs below can be run by
# directly copying the desired program and pasting
# the code to a Python editor such as IDLE...
# For Python and Python IDLE installation and running instructions
# watch this movie: https://youtu.be/3Xy221yv9A8
# The first Python program (01-01.py) has only
# one executable line:
# print("Hello World!")
# and one comment line
# A selection of these example programs are used in courses
# CSCI120 and CSCI165
#################################################
# NOTE: These example programs run on Python 3. #
#################################################
# see https://www.annedawson.net/pythonprograms.html for examples written for Python 2.x
#################################
# READ THE FOLLOWING PARAGRAPH...
# Be aware that there are some significant differences between Python 3
# and earlier versions. For beginner Python programmers, the main ones
# are that the printstatement of Python 2.x is now a printfunction in Python 3,
# (brackets are required after the word print(see program 01-01 below)
# the raw_input function in Python 2.x is replaced by the input function in Python 3,
# and an integer division such as 2/3 in Python 2.x is now a real division
# in Python 3.
# For experienced programmers, also check out
# the range() and string formatting differences outlined here:
# https://inventwithpython.com/appendixa.html
# For experienced programmers, also check out
# IDLE's debugging tools at:
# https://inventwithpython.com/chapter7.html
##############################################################################################
# NOTE FOR USERS OF THIS FILE - all programs shown in this file have been tested with Python 3
##############################################################################################
# 01-01.py
print("Hello World!")
# 01-02.py
thetext = input("Enter some text: ")
print("This is what you entered:")
print(thetext)
# 01-03.py
# Note that \n within quote marks forces a new line to be printed
thetext = input("Enter some text\n")
print("This is what you entered:")
print(thetext)
# 01-04.py
prompt = "Enter a some text "
thetext = input(prompt)
print("This is what you entered:")
print(thetext)
# 02-01.py
total = 0.0
number1 = float(input("Enter the first number: "))
total = total + number1
number2 = float(input("Enter the second number: "))
total = total + number2
number3 = float(input("Enter the third number: "))
total = total + number3
average = total / 3
print("The average is " + str(average))
print("The average is ",average)
################################################################
# #
# 02-02.py #
# Purpose: to demonstrate storage of a floating point number #
# #
# Programmer: Anne Dawson #
# #
# See this resource to find out how the input function works: #
# https://www.annedawson.net/Python3_Input.txt #
# #
# See this resource to find out how important comments are: #
# https://www.annedawson.net/PythonComments.txt #
# #
################################################################
number1 = float(input("Enter the first number: "))
number2 = float(input("Enter the second number: "))
number3 = float(input("Enter the third number: "))
total = number1 + number2 + number3
average = total / 3
print("The average is: ")
print(average)
print("The average is " + str(average))
print("The average is ",average)
# 02-03.py
total = 0.0
count = 0
while count < 3:
number = float(input("Enter a number: "))
count = count + 1
total = total + number
average = total / 3
print("The average is " + str(average))
# 03-01.py
total = 10
# 03-02.py
total = 10
print(total)
# 03-03.py
total = 10
print(total)
print(type (total))
# 03-04.py
print(2 + 4)
print(6 - 4)
print(6 * 3)
print(6 / 3)
print(6 % 3)
print(6 // 3) # floor division: always truncates fractional remainders
print(-5)
print(3**2) # three to the power of 2
# 03-05.py
print(2.0 + 4.0)
print(6.0 - 4.0)
print(6.0 * 3.0)
print(6.0 / 3.0)
print(6.0 % 3.0)
print(6.0 // 3.0) # floor division: always truncates fractional remainders
print(-5.0)
print(3.0**2.0) # three to the power of 2
# 03-06.py
# mixing data types in expressions
# mixed type expressions are "converted up"
# converted up means to take the data type with the greater storage
# float has greater storage (8 bytes) than a regular int (4 bytes)
print(2 + 4.0)
print(6 - 4.0)
print(6 * 3.0)
print(6 / 3.0)
print(6 % 3.0)
print(6 // 3.0) # floor division: always truncates fractional remainders
print(-5.0)
print(3**2.0) # three to the power of 2
# 03-07.py
# these are Boolean expressions which result in a value of
# true or false
# Note that Python stores true as integer 1, and false as integer 0
# but outputs 'true' or 'false' from printstatements
print(7 > 10)
print(4 < 16)
print(4 == 4)
print(4 <= 4)
print(4 >= 4)
print(4 != 4)
# 03-08.py
# these are string objects
print("Hello out there")
print('Hello')
print("Where's the spam?")
print('x')
# 03-09.py
# these are string assignments
a = "Hello out there"
print(a)
b = 'Hello'
print(b)
c = "Where's the spam?"
print(c)
d = 'x'
print(d)
# 03-10.py
a = 'Hello out there'
b = "Where's the spam?"
c = a + b
print(c)
# 03-11.py
a = 'Hello out there'
b = "Where's the spam?"
c = a + b
print(c)
# d = c + 10
# you cannot concatenate a string and an integer
# you must convert the integer to a string first:
d = c + str(10)
print(d)
# 03-12.py
a = "10"
b = '99'
c = a + b
print(c)
print(type(c))
c = int(c)
print(c)
print(type(c))
# 03-13.py
# How to round up a floating point number
# to the nearest integer
# Updated: Monday 24th January 2011, 16:24 PT, AD
x = 1.6
print(x)
x = round(x)
print(x)
# compare the above with
x = 1.6
x = int(x)
print(x)
# 03-14.py
# How to round a float number to 2 decimal places,
# and output that number as $ currency
# printed with a comma after the number of thousands
# i.e. print1234.5678 as $1,234.57
# for a list of Python 3's built-in functions, see the link below:
# http://docs.python.org/py3k/library/functions.html
###########################################################################
# PLEASE NOTE: This program will work correctly for some
# input values, but has not been modified to work in all cases.
###########################################################################
number = 1234.5678
print(number)
number = round(number,2)
print(number)
# the above line rounds the number to 2 decimal places
thousands = number / 1000
print(thousands)
thousands = int(thousands)
print(thousands)
remainder = number % 1000
print(remainder)
pretty_output = "$" + str(thousands) + "," + str(remainder)
print(pretty_output)
# File: 04-01.py
# Purpose: Creating a string object
# Programmer: Anne Dawson
number1 = input("Enter first number:\n")
print(number1, type(number1))
# File: 04-02.py
# Purpose: Converting one data type to another
# Programmer: Anne Dawson
number1 = input("Enter first number:\n")
print(number1, type(number1))
number1 = int(number1)
print(number1, type(number1))
# File: 04-03.py
# Purpose: Displaying an object's memory location
# Programmer: Anne Dawson
number1 = input("Enter first number:\n")
print(number1, type(number1), id(number1))
number1 = int(number1)
print(number1, type(number1), id(number1))
# File: 04-04.py
# Purpose: Examples of use of arithmetic operators
# Programmer: Anne Dawson
print(2 + 4)
print(6 - 4)
print(6 * 3)
print(6 / 3)
print(6 % 3)
print(6 // 3) # floor (integer) division: always truncates fractional remainders
print(-5)
print(3**2) # three to the power of 2
# File: 04-05.py
# Purpose: Examples of use of arithmetic operators with float values
# Programmer: Anne Dawson
print(2.0 + 4.0)
print(6.0 - 4.0)
print(6.0 * 3.0)
print(6.0 / 3.0)
print(6.0 % 3.0)
print(6.0 // 3.0) # floor (integer) division: always truncates fractional remainders
print(-5.0)
print(3.0**2.0) # three to the power of 2
# File: 04-06.py
# Purpose: Examples of use of arithmetic operators
# Programmer: Anne Dawson
# mixing data types in expressions
# mixed type expressions are "converted up"
# converted up means to take the data type with the greater storage
# float has greater storage (8 bytes) than a regular int (4 bytes)
print(2 + 4.0)
print(6 - 4.0)
print(6 * 3.0)
print(6 / 3.0)
print(6 % 3.0)
print(6 // 3.0) # floor division: always truncates fractional remainders
print(-5.0)
print(3**2.0) # three to the power of 2
# File: 04-07.py
# Purpose: Examples of use of Boolean expressions
# Programmer: Anne Dawson
# these are Boolean expressions which result in a value of
# true or false
# Note that Python stores true as integer 1, and false as integer 0
# but outputs 'true' or 'false' from printstatements
# If you input Boolean values, you must input 1 or 0.
print(7 > 10)
print(4 < 16)
print(4 == 4)
print(4 <= 4)
print(4 >= 4)
print(4 != 4)
# File: 04-08.py
# Purpose: Displaying boolean values
# Programmer: Anne Dawson
number = 10
isPositive = (number > 0)
print(isPositive)
# File: 04-09.py
# Purpose: Combining boolean expressions with and
# Programmer: Anne Dawson
age = 25
salary = 55000
print((age > 21) and (salary > 50000))
# File: 04-10.py
# Purpose: The if statement
# Programmer: Anne Dawson
# The condition of the following if statement
# follows the word if, and ends with a colon (:)
# In this example, if x has a value equal to 'spam',
# then 'Hi spam' will be printed.
x = 'spam'
if x == 'spam':
print('Hi spam')
else:
print('not spam')
# Notice the indentation (spacing out) of this code.
# The statement(s) following the if condition (i.e. boolean expression)
# must be indented to the next tab stop. This means you must press
# the Tab button before typing the word print.
# Try removing the tab spaces and see what happens when you attempt to run.
# File: 04-11.py
# Purpose: The if statement with multiple statements
# Programmer: Anne Dawson
# The condition of the following if statement
# follows the word if, and ends with a colon (:)
# In this example, if x has a value equal to 'spam',
# then 'Hi spam\n' will be printed followed by
# "Nice weather we're having"
# followed by 'Have a nice day!'
x = 'spam'
if x == 'spam':
print('Hi spam\n')
print("Nice weather we're having")
print('Have a nice day!')
else:
print('not spam')
# Notice the indentation (spacing out) of this code.
# The statement(s) following the if condition (i.e. boolean expression)
# must be indented to the next tab stop. This means you must press
# the Tab button before typing the word print.
# Try removing the tab spaces and see what happens when you attempt to run.
# File: 04-12.py
# Purpose: The if statement with multiple statements
# Programmer: Anne Dawson
# The condition of the following if statement
# follows the word if, and ends with a colon (:)
# In this example, if x has a value equal to 'spammy',
# then 'Hi spam\n' will be printed followed by
# "Nice weather we're having"
# followed by 'Have a nice day!'
x = 'spam'
if x == 'spammy':
print('Hi spam\n')
print("Nice weather we're having")
print('Have a nice day!')
else:
print('not spam')
print('Not having a good day?')
# Notice the indentation (spacing out) of this code.
# The statement(s) following the if condition (i.e. boolean expression)
# must be indented to the next tab stop. This means you must press
# the Tab button before typing the word print.
# Try removing the tab spaces and see what happens when you attempt to run.
# Program: 04-13.py
# Purpose: A nested if example (an if statement within another if statement)
# Programmer: Anne Dawson
score = input("Enter score: ")
score = int(score)
if score >= 80:
grade = 'A'
else:
if score >= 70:
grade = 'B'
else:
grade = 'C'
print("\n\nGrade is: " + grade)
# Note: \n when typed within quote marks (") will force a new line to be printed
# Program: 04-14.py
# Purpose: A nested if example - using if/else
# Programmer: Anne Dawson
score = input("Enter score: ")
score = int(score)
if score >= 80:
grade = 'A'
else:
if score >= 70:
grade = 'B'
else:
if score >= 55:
grade = 'C'
else:
if score >= 50:
grade = 'Pass'
else:
grade = 'Fail'
print("\n\nGrade is: " + grade)
# Program: 04-15A.py
# Purpose: A nested if example - using if/elif/else
# Programmer: Anne Dawson
score = input("Enter score: ")
score = int(score)
if score > 80 or score == 80:
grade = 'A'
elif score > 70 or score == 70:
grade = 'B'
elif score > 55 or score == 55:
grade = 'C'
elif score > 50 or score == 50:
grade = 'Pass'
else:
grade = 'Fail'
print("\n\nGrade is: " + grade)
# Program: 04-15B.py
# Purpose: A nested if example - using if/elif/else
# Programmer: Anne Dawson
score = input("Enter score: ")
score = int(score)
if score >= 80:
grade = 'A'
elif score >= 70:
grade = 'B'
elif score >= 55:
grade = 'C'
elif score >= 50:
grade = 'Pass'
else:
grade = 'Fail'
print("\n\nGrade is: " + grade)
# File: 04-16.py
# Purpose: Demo of DeMorgan's Laws:
# 1. a Not And is equivalent to an Or with two negated inputs
# 2. a Not Or is equivalent to an And with two negated inputs
# Programmer: Anne Dawson
# Test data: 0 0, 0 1, 1 0, 1 1
# For ***any*** value of x and y, (not(x < 15 and y >= 3)) == (x >= 15 or y < 3)
# Common uses of De Morgan's rules are in digital circuit design
# where it is used to manipulate the types of logic gates.
# Also, computer programmers use them to change a complicated statement
# like IF ... AND (... OR ...) THEN ... into its opposite (and shorter) equivalent.
# http://en.wikipedia.org/wiki/De_Morgan%27s_law
# http://www.coquitlamcollege.com/adawson/DeMorgansLaws.htm
x = int(input("Enter a value for x: "))
y = int(input("Enter a value for y: "))
print((not(x < 15 and y >= 3)))
print((x >= 15 or y < 3))
# Program: 04-17.py
# Purpose: Decision using two conditions linked with an and or an or
# Programmer: Anne Dawson
age = input("Enter your age: ")
age = int(age)
have_own_car = input("Do you own your own car (y/n): ")
if (age > 21) and (have_own_car == 'y'):
print("You are over 21 years old and own your own car")
if (age > 21) and (have_own_car == 'n'):
print("You are over 21 years old and you do NOT own your own car")
if (age == 21) and (have_own_car == 'y'):
print("You are 21 years old and you own your own car")
if (age == 21) and (have_own_car == 'n'):
print("You are 21 years old and you DO NOT own your own car" )
if (age < 21) and (have_own_car == 'y'):
print("You are younger than 21 and you own your own car")
if (age < 21) and (have_own_car == 'n'):
print("You are younger than 21 and you DO NOT own your own car" )
salary = float(input("Enter your annual salary, (e.g. 50000): "))
if (salary > 50000) or (age > 21):
print("you can join our club because you earn more than $50000 OR you are over 21 (or both)")
else:
print("you need to be earning more than 50000 OR be over 21 (or both) to join our club")
# File: 05-01.py
# Purpose: Examples of while loops
# Programmer: Anne Dawson
# You must remember to indent the statements to be repeated.
# They must be repeated to the same level.
# Use the Tab key to indent. The space bar can be used but
# its easier (less typing) to use the space bar
# Used like this, the while loop is said to be
# 'counter-controlled'. In this program, x is acting as a counter.
x = 1
while x < 5:
print('Hi spam')
x = x + 1
print('done')
# File: 05-02.py
# Purpose: Examples of while loops
# Programmer: Anne Dawson
# Used like this, the while loop is said to be
# 'counter-controlled'. In this program, x is acting as a counter.
# You may repeat one statement or multiple statements.
x = 1
while x < 5:
print('Hi spam')
x = x + 1
print('I love spam')
print('done')
print('gone')
# File: 05-03.py
# Purpose: Examples of while loops - the infinite loop
# Programmer: Anne Dawson
# An infinite loop.
# Remember that 1 (or any value other than 0) represents true.
# Press Ctrl-C to interrupt this program run.
x = 1
while x:
print('Hi spam')
x = x + 1
print('I love spam')
print('Press the Ctrl key and the C key together')
print('to interrupt this program...')
print('done')
print('gone')
# File: 05-04.py
# Purpose: Examples of while loops - another infinite loop
# Programmer: Anne Dawson
# An infinite loop.
# Remember that 1 (or any value other than 0) represents true.
# Press Ctrl-C to interrupt this program run.
while 1:
print('Anyone for spam? ')
print('Press the Ctrl key and the C key together')
print('to interrupt this program...')
print('done')
print('gone')
# File: 05-05.py
# Purpose: Example: use of break to end an infinite loop
# Programmer: Anne Dawson
while 1:
print('Spam')
answer = input('Press y to end this loop')
if answer == 'y':
print('Fries with that?')
break
print('Have a ')
print('nice day!')
# File: 05-06.py
# Purpose: Example: use of continue in a loop
# Programmer: Anne Dawson
while 1:
print('Spam')
answer = input('Press y for large fries ')
if answer == 'y':
print('Large fries with spam, mmmm, yummy ')
continue
answer = input('Had enough yet? ')
if answer == 'y':
break
print('Have a ')
print('nice day!')
# File: 05-07.py
# Purpose: Example: 'sentinel-controlled' while loop
# Calculates average score of a class
# Programmer: Anne Dawson
# initialization phase
totalScore = 0 # sum of scores
numberScores = 0 # number of scores entered
# processing phase
score = input( "Enter score, (Enter -9 to end): " ) # get one score
score = int( score ) # convert string to an integer
while score != -9: # -9 is used as a sentinel ( a lookout or sentry value )
totalScore = totalScore + score
numberScores = numberScores + 1
score = input( "Enter score, (Enter -9 to end): " )
score = int( score )
# termination phase
if numberScores != 0: # division by zero would be a run-time error
average = float( totalScore ) / numberScores
print("Class average is", average)
else:
print("No scores were entered")
# File: 05-08.py
# Purpose: Example: the counter-controlled for loop
# Programmer: Anne Dawson
for c in range (10):
print(c)
# Note: range (10) is 0 through 9
# File: 05-09.py
# Purpose: Example: the counter-controlled for loop
# Programmer: Anne Dawson
for c in range (5,10):
print(c)
# Note: range (5,10) is 5 through 9
# File: 05-10.py
# Purpose: Example: 'continue' with the for loop
# Programmer: Anne Dawson
for c in range (1,6):
if c == 3:
continue
print(c)
# File: 05-11.py
# Purpose: Example: 'break' with the for loop
# Programmer: Anne Dawson
for c in range (1,6):
if c == 3:
break
print(c)
# File: 05-12.py
# Purpose: Example: outputting strings and numbers
# in a single printstatement
# Programmer: Anne Dawson
d = 10
c = 75
print('Total is: ', d, 'dollars and', c, ' cents')
# File: 05-13.py
# Purpose: Example: outputting strings and numbers
# in a single printstatement
# using string formatting.
# Reference: https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting
# Programmer: Anne Dawson
firstname = "Anne"
lastname = 'Dawson'
print("My fullname is %s %s" % (firstname,lastname))
print()
# printing decimal or integer numbers in a string
x = 20
y = 75
print('The sum of %d and %d is %d' % (x, y, x + y))
print()
# printing decimal or integer numbers in a string
x = 20
y = 75
print('The sum of %i and %i is %i' % (x, y, x + y))
print()
# printing floating point numbers in a string
x = 20.5126
y = 15.2697
print('The sum of %f and %f is %f' % (x, y, x + y))
print()
# printing floating point numbers to 2 decimal places
x = 20.512
y = 15.269
print('The sum of %0.2f and %0.2f is %0.2f' % (x, y, x + y))
print()
# printing floating point numbers to 3 decimal places
x = 20.512
y = 15.269
print('The sum of %0.3f and %0.3f is %0.3f' % (x, y, x + y))
print()
for number in range(17):
print("The decimal number %d in hexadecimal is %x" % (number,number))
# File: 05-14.py
# Purpose: Example: how to repeat a program at the user's request
# Programmer: Anne Dawson
print("This is the start of the program")
answer = 'y'
while (answer == 'y' or answer == 'Y'):
print("This is a statement from within the while loop")
print("This is another statement from within the while loop")
answer = input("Do you want to run this program again? y/n")
print("Goodbye!")
# File: 05-15.py
# Purpose: Example: how to use a loop within a loop
# a nested while loop
# Programmer: Anne Dawson
print("This is the start of the program")
x = 1
while (x < 6):
print() # prints a new line
print("x = " + str(x),) # the , forces printing of the next item
# to be on the same line
x = x + 1
y = 1
while (y < 6):
print("y = " + str(y),) # the , forces printing on the same line
y = y + 1
'''
Notice that with a loop repeating 5 times,
***within*** a loop that repeats 5 times
means that you can control 25 processes.
'''
# File: 05-16.py
# Purpose: Example: how to use a loop within a loop
# a nested while loop
# Programmer: Anne Dawson
print("This is the start of the program")
x = 1
while (x < 6):
print() # prints a new line
print("x = " + str(x)) # the , forces printing of the next item
# to be on the same line
x = x + 1
y = 1
while (y < 6):
print("y = " + str(y),) # the , forces printing on the same line
y = y + 1
z = 1
while (z < 6):
print("z = " + str(z),) # the , forces printing on the same line
z = z + 1
print() # prints a new line
'''
Notice that with a loop repeating 5 times,
***within*** a loop that repeats 5 times
***within*** a loop that repeats 5 times
means that you can control 125 processes.
'''
# File: 05-17.py
# Purpose: Example: how to use a loop within a loop
# a nested for loop
# Programmer: Anne Dawson
print("This is the start of the program")
for i in range (1,6):
for j in range (1,6):
print("i: " + str(i) + " j: " + str(j) )
print()
'''
Notice that with a loop repeating 5 times,
***within*** a loop that repeats 5 times
means that you can control 25 processes.
'''
# File: 05-18.py
# Purpose: Example: how to use a loop within a loop
# a nested for loop
# Programmer: Anne Dawson
print("This is the start of the program")
for i in range (1,6):
for j in range (1,6):
for k in range (1,6):
print("i: " + str(i) + " j: " + str(j) + " k: " + str(k))
print()
'''
Notice that with a loop repeating 5 times,
***within*** a loop that repeats 5 times
***within*** a loop that repeats 5 times
means that you can control 125 processes.
'''
# File: 06-01.py
# Purpose: Example: using the built-in square root function math.sqrt
# To use any math function, you have to include the statement:
# import math
# in your program - usually at the top, but can be anywhere.
# Programmer: Anne Dawson
import math
print(math.sqrt(16))
print(math.sqrt(16.5))
x = 144
print(math.sqrt(x))
# File: 06-02.py
# Purpose: Example: using the dir function to list out the names
# of available functions in the math module
# Programmer: Anne Dawson
import math
print(math)
print(dir(math))
# File: 06-02B.py
# Purpose: Example: showing functions which have no return statement
# Programmer: Anne Dawson
def greeting():
print("Hello")
def many_greetings(n):
for i in range(n):
print("Hello Again!")
def many_greetings_with_name(n,the_name):
for i in range(n):
print("Hello Again" + the_name + "!")
greeting()
greeting()
greeting()
print() # prints a blank line
for i in range(2):
greeting()
print() # prints a blank line
many_greetings(4)
print() # prints a blank line
x = int(input("How many greetings do you want?: "))
many_greetings_with_name(x," Anne")
# File: 06-03.py
# Purpose: Example: using a programmer-defined function
# Programmer: Anne Dawson
# start of function definition
def cube( y ):
return y * y * y
# end of function definition
# prints the cube of numbers 1 to 5
for x in range(1,6):
print(cube(x))
# the last value of x is 5
print("last value of x is:",x)
# File: 06-04.py
# Purpose: Example: using two programmer-defined functions
# Programmer: Anne Dawson
def cube( y ):
return y * y * y
def doubleIt ( z ):
return 2 * z
print("1 to 5 cubed")
for x in range(1,6):
print(cube(x),)
print()
print()
print("1 to 5 doubled")
for x in range(1,6):
print(doubleIt(x),)
# File: myFunctions.py
# Purpose: two programmer-defined functions
# Programmer: Anne Dawson
def cube( y ):
return y * y * y
def doubleIt ( z ):
return 2 * z
# File: 06-05.py
# Purpose: Example: importing programmer-defined functions
# from its own module file
# Programmer: Anne Dawson
# IMPORTANT: myFunctions.py should be in the same folder as this file
import myFunctions
print("1 to 5 cubed")
for x in range(1,6):
print(myFunctions.cube(x),)
print()
print()
print("1 to 5 doubled" )
for x in range(1,6):
print(myFunctions.doubleIt(x),)
# File: 06-06.py
# Purpose: Example: function with no return statement
# Programmer: Anne Dawson
def times(x):
for i in range(1,11):
print("%d x %d = %d" % (i, x, i * x))
print("This is the 1 times tables:")
times(1)
print("This is the 2 times tables:")
times(2)
# File: 06-07.py
# Purpose: Example: a function with two return statements
# Programmer: Anne Dawson
def division(x,y):
if (y == 0):
print("division by zero not allowed")
return
else:
print(" returning %f divided by %f " % (x, y))
return x / y
print(" 5.0 / 2 returns:")
result = division( 5.0 , 2 )
print(result)
print(" 5.0 / 0 returns:")
result = division( 5.0 , 0 )
print(result)
# File: 06-08.py
# Purpose: Example: a function with no arguments
# Programmer: Anne Dawson
def greeting():
print("Hello out there!")
greeting()
greeting()
greeting()
# File: 06-09.py
# Purpose: Example: a program with a Boolean function
# Programmer: Anne Dawson
def isPositive(x):
if (x >= 0):
return 1 # 1 is true
else:
return 0 # 0 is false
x = float(input("Enter a positive or negative number: "))
result = isPositive(x)
print(result)
print(isPositive(x))
# File: 06-10.py
# Purpose: Example: a polymorphic function
# Programmer: Anne Dawson
def doubleIt(x):
return (2 * x)
y = 3
print(doubleIt(y))
z = "Spam "
print(doubleIt(z))
# This program works because the * operator can be used with
# numbers and with strings. This is an example of Polymorphism.
# Poly means "many" and morph means "form"
# Polymorphism : the meaning of the operations depends on the objects
# being operated on. The * operator is said to be "overloaded"
# An overloaded operator behaves differently depending on
# the type of its operands.
# File: 06-11.py
# Purpose: Example: the scope of a variable
# Programmer: Anne Dawson
# program demonstrating the scope of a variable
# (i.e. where it can be used)
def my_function(n):
print("n in function: ",n)
print("number in function: ",number)
number = 10
print("number in main program: ",number)
my_function(number)
#print(n)
# Uncomment the line above and try to run.
# You will get an error, because....
# n is not known outside of the function my_function.
# Notice however that number is known in the function
# as well as in the main program!
# We say that number has global scope, but n has local scope.
# Local scope means the variable is only available
# in the function where it is defined
# Global scope means the variable is available everywhere in the code.
# File: 06-12.py
# Purpose: Demonstrates the use of Python functions
# Programmer: Anne Dawson
def pause():
input("\n\nPress any key to continue...\n\n")
def quitMessage():
print("Thank you for using this program")
print("Goodbye")
def printThreeLines():
for i in range(1,4):
print('this is line ' + str(i))
def printNineLines():
for i in range(1,4):
printThreeLines()
def startMessage():
print("This program demonstrates the use of Python functions")
pause()
def blank_Line():
print()
def clearScreen():
for i in range(1,26):
blank_Line()
startMessage()
clearScreen()
print("Testing this program")
printNineLines()
pause()
clearScreen()
printNineLines()
blank_Line()
printNineLines()
pause()
clearScreen()
quitMessage()
# File: 07-01.py
# Purpose: Example: creating and using a Python list
# Programmer: Anne Dawson
result = [0,0,0,0,0,0,0,0]
print(result)
result[0] = 75
result[1] = 90
result[4] = 72
print(result)
print(result[0])
print(result[1])
print(result[2])
print(result[3])
print(result[4])
print(result[5])
print(result[6])
print(result[7])
# File: 07-02.py
# Purpose: Example: creating and printing an empty list
# Programmer: Anne Dawson
list1 = []
print(list1)
# the following statement would generate an error
#print(list1[0])
# File: 07-03.py
# Purpose: Example: appending to an empty list
# Programmer: Anne Dawson
list1 = []
print(list1)
list1.append(67)
print(list1[0])
list1.append("spam")
print(list1)
print(list1[0])
print(list1[1])
# the following statement would generate an out-of-range error
#print(list1[2])
# File: 07-04.py
# Purpose: Example: a list of lists
# Programmer: Anne Dawson
list1 = [1,2,3]
print(list1)
list2 = [4,5,6]
print(list2)
list3=[list1,list2]
print(list3)
print(list3[0])
print(list3[1])
# File: 07-05.py
# Purpose: Example: accessing the last item in a list
# Programmer: Anne Dawson
list1 = [1,2,3,6,7,8,9,10]
print(list1)
print(list1[0])
print(list1[1])
print(list1[-1])
print(list1[-2])
# File: 07-06.py
# Purpose: Example: deleting items from a list
# Programmer: Anne Dawson
list1 = [1,2,3,4,5,6,7,8,9,10]
print(list1)
del list1[0]
del list1[-1]
print(list1)
# File: 07-07.py
# Purpose: Example: repeating lists
# Programmer: Anne Dawson
list1 = [1,2,3]
print(list1)
print(list1 * 3)
print(list1)
list1 = list1 * 2
print(list1)
# File: 07-08.py
# Purpose: Example: concatenating lists
# Programmer: Anne Dawson
list1 = [1,2,3]
print(list1)
list2 = [4,5,6]
print(list2)
list1 = list1 + list2
print(list1)
list1 = list1 + list1
print(list1)
# File: 07-09.py
# Purpose: Example: ist indexing
# Programmer: Anne Dawson
list1 = ["Anne", "Dawson", 666]
print(list1[0], list1[2])
# File: 07-10.py
# Purpose: Example: list indexing
# Programmer: Anne Dawson
list1 = [2,4,6,8,10,12,14,16,18,20]
print(list1[0:1],list1[5:7])
# File: 07-11.py
# Purpose: Example: finding the length of a list
# Programmer: Anne Dawson
list1 = ["Anne","was",'here','testing',1,2,3]
list2 = [1,2,3,4]
list3 = []
print(len(list1), len(list2), len(list3))
# File: 07-12.py
# Purpose: Example: list iteration
# Programmer: Anne Dawson
list2 = [1,2,3,"Spam",4,5]
for i in list2:
print(i, end=" ")
# File: 07-13.py
# Purpose: Example: list membership
# Programmer: Anne Dawson
list2 = [1,2,3,"Spam",4,5]
print("Spam" in list2)
# File: 07-14.py
# Purpose: Example: a selection of list methods
# Programmer: Anne Dawson
list2 = ["B","C","A"]
print(list2)
list2.extend(["X","Y"]) # extends the list
print(list2)
list2.pop() # removes last item from the list
print(list2)
list2.pop()
print(list2)
list2.reverse() # reverses the order of the items in the list
print(list2)
list2.append("S")
print(list2)
list2.sort() # sorts the list into ascending order
print(list2)
list2.reverse() # reverses the order of the items in the list
print(list2)
# File: 07-15.py
# Purpose: Example: a 2D list
# Programmer: Anne Dawson
tictactoe = [[1,2,3], [4,5,6], [7,8,9]]
print(tictactoe[0])
print(tictactoe[1])
print(tictactoe[2])
print()
row = 1
column = 0
print("row " + str(row) + " column " + str(column) + " has value")
print(tictactoe[row][column])
row = 2
column = 2
print("row " + str(row) + " column " + str(column) + " has value")
print(tictactoe[row][column])
print()
print()
tictactoe[2][2] = 0
print("After changing the value at row 2 and column 2 to 0: ")
print()
print(tictactoe[0])
print(tictactoe[1])
print(tictactoe[2])
# File: 07-16.py
# Purpose: Differences in range() with Python 2 and Python 3
# Programmer: Anne Dawson
# The range() function works differently in Python 2 and Python 3.
# In Python 2, the range function returns a list,
# which may take up a large amount of memory, depending on the size and nature of the list.
# In Python 3, the range function will always take the same (small) amount of memory,
# no matter the size of the range it represents
# as it only stores the start, stop and step values,
# calculating individual items and subranges as needed.
# See: https://docs.python.org/3/tutorial/controlflow.html#the-range-function
# and for much more detail, see:
# See: https://docs.python.org/3/library/stdtypes.html?highlight=range#range
# You can always convert a range to a list by using the list function,
# as shown in the following code.
# Example run follows:
'''
>>>
range(0, 10)
<class 'range'>
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
<class 'list'>
>>>
'''
x = range(10)
print(x)
print(type(x))
x = list(range(10))
print(x)
print(type(x))
# File: 08-01.py
# Purpose: Example: strings
# Programmer: Anne Dawson
print('Anne was here')
print("9396633")
# Note that you can printa string over several lines
# if you contain it within triple quotes marks:
print('''Anne was here
on Tuesday
28th February 2023''')
# File: 08-02.py
# Purpose: Example: using an apostrophe within a string
# and using double quote marks within a string
# Programmer: Anne Dawson
print("This is Anne's spam")
print("This is Anne's spam and these are Jake's eggs" )
# You can also printa " within a string enclosed in single quotes:
print('Here is a double quote ", and "more"')
# File: 08-03.py
# Purpose: Example: multiplying numbers and
# multiplying strings
# Programmer: Anne Dawson
print(3 * 4)
print(30 * 4)
print("3" * 4)
print("30" * 4)
# File: 08-04.py
# Purpose: Example: string concatenation
# Programmer: Anne Dawson
print("Anne " + "was " + ("here " * 3))
# File: 08-05.py
# Purpose: Example: string indexing
# Programmer: Anne Dawson
s1 = "Anne Dawson"
print(s1[0],s1[5])
# File: 08-06.py
# Purpose: Example: string slicing
# Programmer: Anne Dawson
s1 = "Anne Dawson"
print(s1[0:1],s1[5:7])
print(s1[6:9])
# File: 08-07.py
# Purpose: Example: finding the length of a string
# Programmer: Anne Dawson
s1 = "Anne"
s2 = "Dawson"
s3 = ""
print(len(s1),end=" ")
print(len(s2),end=" ")
print(len(s3))
# File: 08-08.py
# Purpose: Example: the %s string formatting code
# Programmer: Anne Dawson
print('Python is a %s language.' % 'great')
# File: 08-09.py
# Purpose: Example: finding a string within a string
# Programmer: Anne Dawson
s1 = 'spamandeggs'
x = s1.find('and')
print(x)
# File: 08-10.py
# Purpose: Example: finding a string within a string
# Programmer: Anne Dawson
s1 = 'spam and eggs'
s1.replace('and','without')
print(s1)
# the above shows that strings are immutable (cannot change)
s2 = s1.replace('and','without')
print(s2)
# File: 08-11.py
# Purpose: Example: escape sequences within a string
# Programmer: Anne Dawson
s = 'one\ntwo\tthree'
print(s)
# File: 08-12.py
# Purpose: Example: an escape sequence counts as one character
# Programmer: Anne Dawson
s = 'one\ntwo\tthree'
print(s)
print(len(s))
# File: 08-13.py
# Purpose: Example: iteration and membership with strings
# Programmer: Anne Dawson
s = 'Anne was here'
for c in s:
print(c, end=" ")
print('w' in s, end=" ")
print(' ' in s, end=" ")
print('x' in s)
# 08-14.py
# Anne Dawson
# Demonstration of printing Unicode characters
# For explanation, see:
# http://www.network-theory.co.uk/docs/pytut/tut_17.html
# For character charts go to:
# https://www.unicode.org/Public/10.0.0/charts/CodeCharts.pdf
# BEST VIEWED USING FIREFOX BROWSER!
# \u2588 is a Full Block which can be used to build up a solid square
str1 = "Hello\u2588out there" # solid block within text
print(str1)
str1 = '\u2588\u2588' #two full block characters
print(str1)
print()
print()
print("two lines of two full blocks")
print(str1)
print(str1)
print()
print()
# Note: a space is \u0020
print('two lines of two full blocks, two spaces, two full blocks:')
str1 = '\u2588\u2588\u2588\u2588\u0020\u0020\u0020\u0020\u2588\u2588\u2588\u2588'
print(str1)
print(str1)
print()
print()
print('two lines of two full blocks, the number 17 and two full blocks:')
str1 = '\u2588\u2588\u2588\u2588\u0020\u0020' + '17' + '\u2588\u2588\u2588\u2588'
print(str1)
str1 = '\u2588\u2588\u2588\u2588\u0020\u0020\u0020\u0020\u2588\u2588\u2588\u2588'
print(str1)
# File: 09-01.py
# Purpose: Example: a program which uses a file
# Programmer: Anne Dawson
file1 = open('C:\\temp\\file1.txt','r')
# the line above opens C:\temp\file1.txt for reading
string = file1.readline()
print(string)
# File: 09-02.py
# Purpose: Example: a program which uses a file
# Programmer: Anne Dawson
file1 = open("C:\\temp\\tester2.txt","w")
print(file1) # prints out details about the file
file1.write("Today is Monday\n")
file1.write("Tomorrow is Tuesday")
file1.close()
# File: 09-03.py
# Purpose: Example: a program which uses a file
# Programmer: Anne Dawson
file2 = open("C:\\temp\\tester2.txt","r")
print(file2) # prints out details about the file
string1 = file2.read()
print(string1)
file2.close()
file2 = open("C:\\temp\\tester2.txt","r")
string1 = file2.read(5)
print(string1)
string1 = file2.read(5)
print(string1)
string1 = file2.read(5)
print(string1)
file2.close()
# File: 09-04.py
# Purpose: Example: a program which uses a file
# Programmer: Anne Dawson
def copyFile(oldFile, newFile):
f1 = open(oldFile, "r")
f2 = open(newFile, "w")
while 1:
text = f1.read(50)
if text == "":
break
f2.write(text)
f1.close()
f2.close()
return
filecopy = "C:\\temp\\tester2copy.txt" #this file will be created
fileold = "C:\\temp\\tester2.txt" # existing file
copyFile(fileold, filecopy)
# File: 09-05.py
# Purpose: Example: a program which uses a file
# Programmer: Anne Dawson
filename = input('Enter a file name: ')
try:
f = open (filename, "r")
except:
print('There is no file named', filename )
# File: 10-01.py
# Purpose: Example: sequential search of a list
# Programmer: Anne Dawson
list1 = [11,27,36,44,51,22,65,1,78]
numbertofind = int(input("Enter a number\n"))
found = 0
for i in list1:
if numbertofind == i:
print(numbertofind, " at index: ",list1.index(numbertofind))
found = 1
if found == 0:
print("Number not found")
# File: 10-02.py
# Purpose: Example: sequential search of a list
# Programmer: Anne Dawson
mylist = [10,11,3,4,55,12,23,14,16]
n = len(mylist)
print(n)
for i in range(n):
print(mylist[i], end=" ")
search = int(input("\nPlease enter a number to search for: "))
print(search)
found = False
for i in range(n):
if mylist[i] == search:
found = True
index = i
print()
if found == True:
print(str(search) + " found at index " + str(index))
else:
print(str(search) + " not found")
# File: 10-03.py
# Purpose: Sequential (also known as linear) search
# Checking the number of steps to find the target
# Programmer: Anne Dawson
list1 = [11,27,36,44,51,22,65,1,78]
numbertofind = int(input("Enter a number\n"))
found = 0
steps = 0
for i in list1:
steps = steps + 1
if numbertofind == i:
print(numbertofind, " at index: ",list1.index(numbertofind))
found = 1
if found == 1:
break
if found == 0:
print("Number not found")
print("Steps taken to find the number: ",steps)
# File: 10-04.py binarysearch.py
# Programmer: Anne Dawson
# Python 3
def binarysearch(mylist,target):
left = 0
right = len(mylist)
while (left < right-1):
mid = int((right+left)/2)
number_at_mid = mylist[mid]
if (target == number_at_mid):
return True
if (target < number_at_mid):
right = mid
else:
left = mid
if (left >= right):
return False
if ( (left == (right-1)) and (mylist[left] == target) ):
return True
return False
n = int(input("Enter number of numbers to input: "))
count = 0
mylist = []
while (count < n):
count = count + 1
x = int(input("Enter value for number " + str(count) + ": "))
mylist.append(x)
print(mylist)
mylist.sort()
print(mylist)
repeat = "y"
while (repeat == "y" or repeat == "Y"):
mytarget = int(input("Enter number to find: "))
if binarysearch(mylist,mytarget):
print("Found!")
else:
print("NOT Found!")
repeat = input("Another search? (y/n)")
print("\n\nThank you for using this program")
# File: 10-05.py binarysearch.py
# Programmer: Anne Dawson
# Purpose: Binary search -
# checking the number of steps to find the target
def binarysearch(mylist,target):
left = 0
right = len(mylist)
steps = 0
while (left < right-1):
steps = steps + 1
mid = int((right+left)/2)
number_at_mid = mylist[mid]
print("Steps taken to find the number: ",steps)
if (target == number_at_mid):
return True
if (target < number_at_mid):
right = mid
else:
left = mid
if (left >= right):
return False
if ( (left == (right-1)) and (mylist[left] == target) ):
return True
return False
mylist = [11,27,36,44,51,22,65,1,78]
print(mylist)
mylist.sort()
print(mylist)
repeat = "y"
while (repeat == "y" or repeat == "Y"):
mytarget = int(input("Enter number to find: "))
if binarysearch(mylist,mytarget):
print("Found!")
else:
print("NOT Found!")
repeat = input("Another search? (y/n)")
print("\n\nThank you for using this program")
# File: 10-06.py biglist.py
# Programmer: Anne Dawson
# Purpose: to create a list of 10,000 unique random integers
# in the range 1 through 20,000
import random
numberslist = []
number = 0
while number < 10000:
value = random.randint(1,20000)
if not(value in numberslist):
numberslist.append(value)
number = number + 1
print(numberslist)
# File: 10-07.py bubblesort.py
# Purpose: Example: a program which demonstrates a bubble sort on
# a list of 10 random integers
# Programmer: Anne Dawson
import random
# define the bubble sort function
def sort(values):
length = len(values)
for time in range(0, length-1):
for position in range(0, (length-time-1)):
if values[position] > values[position+1]:
temp = values[position]
values[position] = values[position+1]
values[position+1] = temp
# generate a list of ten random numbers
numbers = []
number = 0
while number < 10:
value = random.randint(1,100)
if not(value in numbers):
numbers.append(value)
number = number + 1
# show unsorted list, sort the list, and show sorted list
print("Before:", numbers)
sort(numbers)
print("After :", numbers)
# File: 10-08.py bubblesort.py
# Purpose: Example: a program which demonstrates a bubble sort on
# a list of 10 random integers, counting the steps taken to sort the list
# Programmer: Anne Dawson
import random
# define the bubble sort function
def sort(values):
steps = 0
length = len(values)
for time in range(0, length-1):
for position in range(0, (length-time-1)):
if values[position] > values[position+1]:
temp = values[position]
values[position] = values[position+1]
values[position+1] = temp
steps = steps + 1
print("Steps taken to sort the list: ",steps)
# generate a list of ten random numbers
numbers = []
number = 0
while number < 10:
value = random.randint(1,100)
if not(value in numbers):
numbers.append(value)
number = number + 1
# show unsorted list, sort the list, and show sorted list
print("Before:", numbers)
sort(numbers)
print("After :", numbers)
# File: 12-01.py
# Purpose: Example: a recursive function
# Programmer: Anne Dawson
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n-1)
print(" 5! has a value of: ",)
result = factorial(5)
print(result)
print(" 4! has a value of:",)
result = factorial(4)
print(result)
OOP
# File: 13-01.py
# Purpose: OOP Example: How to create objects of the Person class
# and how to inspect the state of those objects.
# Programmer: Anne Dawson
# References: https://www.annedawson.net/Python3_Intro_OOP.odp
# https://www.annedawson.net/Python3_Prog_OOP.odp
class Person():
'''Instantiates a Person object with given name. '''
def __init__(self, first_name, last_name):
'''Initializes private instance variables _firstname and _lastname. '''
self._firstname = first_name
self._lastname = last_name
def __str__(self):
'''Returns the state of the Person object. '''
return self._firstname + " " + self._lastname
print(Person.__doc__) # prints the docstring for the class
person1 = Person("Anne","Dawson")
person2 = Person("Tom","Lee")
print(person1)
print(person2)
# File: 13-02.py
# Purpose: OOP Example: How to use accessor methods
# Programmer: Anne Dawson
# References: https://www.annedawson.net/Python3_Intro_OOP.odp
# https://www.annedawson.net/Python3_Prog_OOP.odp
class Person():
'''Instantiates a Person object with given name. '''
def __init__(self, first_name, last_name):
'''Initializes private instance variables _firstname and _lastname. '''
self._firstname = first_name
self._lastname = last_name
def __str__(self):
'''Returns the state of the Person object. '''
return self._firstname + " " + self._lastname
def getFirstname(self): # accessor method
'''Returns the instance variable _firstname. '''
return self._firstname
def getLastname(self): # accessor method
'''Returns the instance variable _lastname. '''
return self._lastname
print(Person.__doc__) # prints the docstring for the class
person1 = Person("Anne","Dawson")
person2 = Person("Tom","Lee")
print(person1) # calls the __str__ method implicitly on person1 object
print(person2) # calls the __str__ method implicitly on person2 object
print(Person.getFirstname.__doc__) # prints the docstring for the getFirstname method
print(person1.getFirstname())
print(person1.getLastname())
print(person2.getFirstname())
print(person2.getLastname())
# File: 13-03.py
# Purpose: OOP Example: How to use accessor and mutator methods
# Programmer: Anne Dawson
# References: https://www.annedawson.net/Python3_Intro_OOP.odp
# https://www.annedawson.net/Python3_Prog_OOP.odp
class Person():
'''Instantiates a Person object with given name. '''
def __init__(self, first_name, last_name):
'''Initializes private instance variables _firstname and _lastname. '''
self._firstname = first_name
self._lastname = last_name
def __str__(self):
'''Returns the state of the Person object. '''
return self._firstname + " " + self._lastname
def getFirstname(self): # accessor method
'''Returns the instance variable _firstname. '''
return self._firstname
def getLastname(self): # accessor method
'''Returns the instance variable _lastname. '''
return self._lastname
def setFirstname(self,newFirstname): # mutator method
'''Assign a value to the instance variable _firstname. '''
self._firstname = newFirstname
def setLastname(self,newLastname): # mutator method
'''Assign a value to the instance variable _lastname. '''
self._lastname = newLastname
print(Person.__doc__) # prints the docstring for the class
person1 = Person("Anne","Dawson")
person2 = Person("Tom","Lee")
print(person1) # calls the __str__ method implicitly on person1 object
print(person2) # calls the __str__ method implicitly on person2 object
print(Person.getFirstname.__doc__) # prints the docstring for the getFirstname method
print(person1.getFirstname())
print(person1.getLastname())
print(person2.getFirstname())
print(person2.getLastname())
person1.setFirstname("Annie")
print(person1.getFirstname())
# File: 13-04.py
# Purpose: OOP Example: How to use accessor, mutator and regular methods
# Programmer: Anne Dawson
# References: https://www.annedawson.net/Python3_Intro_OOP.odp
# https://www.annedawson.net/Python3_Prog_OOP.odp
class Person():
'''Instantiates a Person object with given name. '''
def __init__(self, first_name, last_name):
'''Initializes private instance variables _firstname and _lastname. '''
self._firstname = first_name
self._lastname = last_name
def __str__(self):
'''Returns the state of the Person object. '''
return self._firstname + " " + self._lastname
def getFirstname(self): # accessor method
'''Returns the instance variable _firstname. '''
return self._firstname
def getLastname(self): # accessor method
'''Returns the instance variable _lastname. '''
return self._lastname
def setFirstname(self,newFirstname): # mutator method
'''Assign a value to the instance variable _firstname. '''
self._firstname = newFirstname
def setLastname(self,newLastname): # mutator method
'''Assign a value to the instance variable _lastname. '''
self._lastname = newLastname
def reverseName(self): # method
'''Reverses the full name '''
return self._lastname + " " + self._firstname
print(Person.__doc__) # prints the docstring for the class
person1 = Person("Anne","Dawson")
person2 = Person("Tom","Lee")
print(person1) # calls the __str__ method implicitly on person1 object
print(person2) # calls the __str__ method implicitly on person2 object
print(Person.getFirstname.__doc__) # prints the docstring for the getFirstname method
print(person1.getFirstname())
print(person1.getLastname())
print(person2.getFirstname())
print(person2.getLastname())
person1.setFirstname("Annie")
print(person1.getFirstname())
print(person1.reverseName())
# File: 13-05.py
# Purpose: OOP Example: Student class inherits from Person class
# Programmer: Anne Dawson
# References: https://www.annedawson.net/Python3_Intro_OOP.odp
# https://www.annedawson.net/Python3_Prog_OOP.odp
class Person():
'''Instantiates a Person object with given name. '''
def __init__(self, first_name, last_name):
'''Initializes private instance variables _firstname and _lastname. '''
self._firstname = first_name
self._lastname = last_name
def __str__(self):
'''Returns the state of the Person object. '''
return self._firstname + " " + self._lastname
def getFirstname(self): # accessor method
'''Returns the instance variable _firstname. '''
return self._firstname
def getLastname(self): # accessor method
'''Returns the instance variable _lastname. '''
return self._lastname
def setFirstname(self,newFirstname): # mutator method
'''Assign a value to the instance variable _firstname. '''
self._firstname = newFirstname
def setLastname(self,newLastname): # mutator method
'''Assign a value to the instance variable _lastname. '''
self._lastname = newLastname
def reverseName(self): # method
'''Reverses the full name '''
return self._lastname + " " + self._firstname
class Student(Person):
'''Instantiates a Student object with given name. '''
def __init__(self, first_name, last_name, student_number=0, G_P_A=0):
'''Initializes private instance variables _firstname, _lastname, _SN and _GPA. '''
super().__init__(first_name, last_name) # import base's parameters
'''Initializes private instance variables _firstname and _lastname. '''
self._SN = student_number
self._GPA = G_P_A
def __str__(self):
'''Returns the state of the Student object. '''
return self._firstname + " " + self._lastname + " " + str(self._SN) + " " + str(self._GPA)
def getSN(self): # accessor method
'''Returns the instance variable _SN. '''
return self._SN
def getGPA(self): # accessor method
'''Returns the instance variable _GPA. '''
return self._GPA
def setSN(self,newSN): # mutator method
'''Assign a value to the instance variable _SN. '''
self._SN = newSN
def setGPA(self,newGPA): # mutator method
'''Assign a value to the instance variable _GPA. '''
self._GPA = newGPA
def reverseName(self): # method
'''Reverses the full name '''
return self._lastname + " " + self._firstname + " " + str(self._GPA)
print(Student.__doc__) # prints the docstring for the class
student1 = Student("Carol","Wong")
student2 = Student("Bill","Wang")
print(student1) # calls the __str__ method implicitly on person1 object
print(student2) # calls the __str__ method implicitly on person2 object
print(Student.getFirstname.__doc__) # prints the docstring for the getFirstname method
print(Student.getGPA.__doc__) # prints the docstring for the getGPA method
print(student1.getFirstname())
print(student1.getLastname())
print(student2.getFirstname())
print(student2.getLastname())
student1.setFirstname("Louisa")
print(student1.getFirstname())
print(student1.reverseName()) # The reverseName method of the Student class
# overrides the same method of the Parent class.
# This is an example of polymorphism
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