Non-Programmer's Tutorial for Python 3/Print version

Non-Programmers' Tutorial For Python 3

# Python is easy to learn
print("Hello, World!")

Hello, World!

Halt!
Who Goes there? Josh
You may pass, Josh

nano
emacs
vi
idle3
python-tools
$ tar -xvzf ~/Download/Python-3.7.4.tgz
... list of files as they are uncompressed 

$ cd Python-3.7/
$ ./configure --prefix=$HOME/python3_install
 ... lots of output.  Watch for error messages here ... 
$ make
 ... even more output.  Hopefully no error messages ... 
$ make install

$ ~/python3_install/bin/python3
Python 3.7.4 (... size and date information ...)
[GCC 9.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

--prefix=$HOME/python3_install
/usr/local
tk
tcl
make
echo %PATH%

PATH
C:\Python37
C:\Python37
C:\Python37\Scripts

#stops console from exiting
end_prog = ""
while end_prog != "q":
        end_prog = input("type q to quit")

Python 3.0 (r30:67503, Dec 29 2008, 21:31:07) 
[GCC 4.3.2 20081105 (Red Hat 4.3.2-7)] on linux2
Type "copyright", "credits" or "license()" for more information.

    ****************************************************************
    Personal firewall software may warn about the connection IDLE
    makes to its subprocess using this computer's internal loopback
    interface.  This connection is not visible on any external
    interface and no data is sent to or received from the Internet.
    ****************************************************************

IDLE 3.0      
>>> 

print("Hello, World!")

.py
-
_

å
ɓ
ç
ð
é
õ
ü
print.py
math.py
list.py
#!/usr/bin/env python3

print("Hello, World!")

Hello, World!

print("Jack and Jill went up a hill")
print("to fetch a pail of water;")
print("Jack fell down, and broke his crown,")
print("and Jill came tumbling after.")

Jack and Jill went up a hill
to fetch a pail of water;
Jack fell down, and broke his crown,
and Jill came tumbling after.

print("Jack and Jill went up a hill")

Jack and Jill went up a hill

print("to fetch a pail of water;")

to fetch a pail of water;

print("Hello, World!")

print("Hello, World!")

print("Hello, World!\nWhat should I do?")

Hello, World!
What should I do?

print("Hello, World!")

print("Hello, World!\n")

print("2 + 2 is", 2 + 2)
print("3 * 4 is", 3 * 4)
print("100 - 1 is", 100 - 1)
print("(33 + 2) / 5 + 11.5 is", (33 + 2) / 5 + 11.5)

2 + 2 is 4
3 * 4 is 12
100 - 1 is 99
(33 + 2) / 5 + 11.5 is 18.5

print("2 + 2 is", 2 + 2)

# Not quite PI, but a credible simulation
print(22 / 7)

3.14285714286

# Output PI on the screen
print(22 / 7) # Well, just a good approximation

print("Something's rotten in the state of Denmark.")
print("                -- Shakespeare")

Something's rotten in the state of Denmark.
                -- Shakespeare

# This is not quite true outside of USA
# and is based on my dim memories of my younger years
print("Firstish Grade")
print("1 + 1 =", 1 + 1)
print("2 + 4 =", 2 + 4)
print("5 - 2 =", 5 - 2)
print()
print("Thirdish Grade")
print("243 - 23 =", 243 - 23)
print("12 * 4 =", 12 * 4)
print("12 / 3 =", 12 / 3)
print("13 / 3 =", 13 // 3, "R", 13 % 3)
print()
print("Junior High")
print("123.56 - 62.12 =", 123.56 - 62.12)
print("(4 + 3) * 2 =", (4 + 3) * 2)
print("4 + 3 * 2 =", 4 + 3 * 2)
print("3 ** 2 =", 3 ** 2)

Firstish Grade
1 + 1 = 2
2 + 4 = 6
5 - 2 = 3

Thirdish Grade
243 - 23 = 220
12 * 4 = 48
12 / 3 = 4
13 / 3 = 4 R 1

Junior High
123.56 - 62.12 = 61.44
(4 + 3) * 2 = 14
4 + 3 * 2 = 10
3 ** 2 = 9

print("Ada Lovelace", "born on", "November 27, 1852")

print("Albert Einstein", "born on", "14 March 1879")

print(("John Smith"), ("born on"), ("14 March 1879"))

print("5**5 = ", 5**5)
print("6*7 = ", 6*7)
print("56/8 = ", 56/8)
print("14//6 = ", 14//6)
print("14%6 = ", 14%6)
print("5+6 = ", 5+6)
print("9-0 = ", 9-0)

print("Halt!")
user_input = input("Who goes there? ")
print("You may pass,",  user_input)

Halt!
Who goes there? Josh
You may pass, Josh

Halt!
Who goes there?

a = 123.4
b23 = 'Spam'
first_name = "Bill"
b = 432
c = a + b
print("a + b is",c)
print("first_name is",first_name)
print("Sorted Parts, After Midnight or",b23)

a + b is 555.4
first_name is Bill
Sorted Parts, After Midnight or Spam

value1 == Pim
value2 == "Pim"

a = 1
print(a)
a = a + 1
print(a)
a = a * 2
print(a)

1
2
4

number = float(input("Type in a number: "))
integer = int(input("Type in an integer: "))
text = input("Type in a string: ")
print("number =", number)
print("number is a", type(number))
print("number * 2 =", number * 2)
print("integer =", integer)
print("integer is a", type(integer))
print("integer * 2 =", integer * 2)
print("text =", text)
print("text is a", type(text))
print("text * 2 =", text * 2)

Type in a number: 12.34
Type in an integer: -3
Type in a string: Hello
number = 12.34
number is a <class 'float'>
number * 2 = 24.68
integer = -3
integer is a <class 'int'>
integer * 2 = -6
text = Hello
text is a <class 'str'>
text * 2 = HelloHello

>>> print("This" + " " + "is" + " joined.")
This is joined.
>>> print("Ha, " * 5)
Ha, Ha, Ha, Ha, Ha, 
>>> print("Ha, " * 5 + "ha!")
Ha, Ha, Ha, Ha, Ha, ha!
>>> print(3 - 1)
2
>>> print("3" - "1")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for -: 'str' and 'str'
>>> 

# This program calculates rate and distance problems
print("Input a rate and a distance")
rate = float(input("Rate: "))
distance = float(input("Distance: "))
time=(distance/ rate)
print("Time:", time)

Input a rate and a distance
Rate: 5
Distance: 10
Time: 2.0

Input a rate and a distance
Rate: 3.52
Distance: 45.6
Time: 12.9545454545

# This program calculates the perimeter and area of a rectangle
print("Calculate information about a rectangle")
length = float(input("Length: "))
width = float(input("Width: "))
Perimeter=(2 * length + 2 * width) 
print("Area:", length * width)
print("Perimeter:",Perimeter)

Calculate information about a rectangle
Length: 4
Width: 3
Area: 12.0
Perimeter: 14.0

Calculate information about a rectangle
Length: 2.53
Width: 5.2
Area: 13.156
Perimeter: 15.46

# This program converts Fahrenheit to Celsius
fahr_temp = float(input("Fahrenheit temperature: "))
celc_temp = (fahr_temp - 32.0) *( 5.0 / 9.0)
print("Celsius temperature:", celc_temp)

Fahrenheit temperature: 32
Celsius temperature: 0.0

Fahrenheit temperature: -40
Celsius temperature: -40.0

Fahrenheit temperature: 212
Celsius temperature: 100.0

Fahrenheit temperature: 98.6
Celsius temperature: 37.0

string1 = input('String 1: ')
string2 = input('String 2: ')
float1 = float(input('Number 1: '))
float2 = float(input('Number 2: '))
print(string1 + string2)
print(float1 * float2)

a = 0            # FIRST, set the initial value of the variable a to 0(zero).
while a < 10:    # While the value of the variable a is less than 10 do the following:
    a = a + 1    # Increase the value of the variable a by 1, as in: a = a + 1! 
    print(a)     # Print to screen what the present value of the variable a is.
                 # REPEAT! until the value of the variable a is equal to 9!? See note. 

                 # NOTE:
                 # The value of the variable a will increase by 1
                 # with each repeat, or loop of the 'while statement BLOCK'.
                 # e.g. a = 1 then a = 2 then a = 3 etc. until a = 9 then...
                 # the code will finish adding 1 to a (now a = 10), printing the 
                 # result, and then exiting the 'while statement BLOCK'. 
                 #              --
                 # While a < 10: |
                 #     a = a + 1 |<--[ The while statement BLOCK ]
                 #     print (a) |
                 #              --

1
2
3
4
5
6
7
8
9
10

a = 1
s = 0
print('Enter Numbers to add to the sum.')
print('Enter 0 to quit.')
while a != 0:                           
    print('Current Sum:', s)            
    a = float(input('Number? '))        
    s = s + a                            
print('Total Sum =', s)

Enter Numbers to add to the sum.
Enter 0 to quit.
Current Sum: 0
Number? 200
Current Sum: 200.0
Number? -15.25
Current Sum: 184.75
Number? -151.85
Current Sum: 32.9
Number? 10.00
Current Sum: 42.9
Number? 0
Total Sum = 42.9

while 1 == 1:
   print("Help, I'm stuck in a loop.")

==
<
# This program calculates the Fibonacci sequence
a = 0
b = 1
count = 0
max_count = 20

while count < max_count:
    count = count + 1
    print(a, end=" ")  # Notice the magic end=" " in the print function arguments  
                       # that keeps it from creating a new line.
    old_a = a    # we need to keep track of a since we change it.
    a = b
    b = old_a + b
print()  # gets a new (empty) line.

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181

# Simplified and faster method to calculate the Fibonacci sequence
a = 0
b = 1
count = 0
max_count = 10

while count < max_count:
    count = count + 1
    print(a, b, end=" ")  # Notice the magic end=" "
    a = a + b    
    b = a + b
print()  # gets a new (empty) line.

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181

a = 0
b = 1
count = 0
maxcount = 20

#once loop is started we stay in it
while count < maxcount:
    count += 1
    olda = a
    a = a + b
    b = olda
    print(olda,end=" ")
print()

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181

# Waits until a password has been entered.  Use Control-C to break out without
# the password

#Note that this must not be the password so that the 
# while loop runs at least once.
password = str()

# note that != means not equal
while password != "unicorn":
    password = input("Password: ")
print("Welcome in")

Password: auo
Password: y22
Password: password
Password: open sesame
Password: unicorn
Welcome in

name = input("What is your UserName: ")
password = input("What is your Password: ")
print("To lock your computer type lock.")
command = None
input1 = None
input2 = None
while command != "lock":
    command = input("What is your command: ")
while input1 != name:
    input1 = input("What is your username: ")
while input2 != password:
    input2 = input("What is your password: ")
print("Welcome back to your system!")

name = input('Set name: ')
password = input('Set password: ')
while 1 == 1:
    nameguess=""
    passwordguess=""
    key=""
    while (nameguess != name) or (passwordguess != password):
        nameguess = input('Name? ')
        passwordguess = input('Password? ')
    print("Welcome,", name, ". Type lock to lock.")
    while key != "lock":
        key = input("")

n = int(input("Number? "))
if n < 0:
   print("The absolute value of", n, "is", -n)
else:
   print("The absolute value of", n, "is", n)

Number? -34
The absolute value of -34 is 34

Number? 1
The absolute value of 1 is 1

a = 0
while a < 10:
    a = a + 1
    if a > 5:
        print(a, ">", 5)
    elif a <= 3:
        print(a, "<=", 3)
    else:
        print("Neither test was true")

1 <= 3
2 <= 3
3 <= 3
Neither test was true
Neither test was true
6 > 5
7 > 5
8 > 5
9 > 5
10 > 5

# This Program Demonstrates the use of the == operator
# using numbers
print(5 == 6)
# Using variables
x = 5
y = 8
print(x == y)

False
False

# Plays the guessing game higher or lower 

# This should actually be something that is semi random like the
# last digits of the time or something else, but that will have to
# wait till a later chapter.  (Extra Credit, modify it to be random
# after the Modules chapter)
number = 7
guess = -1

print("Guess the number!")
while guess != number:
    guess = int(input("Is it... "))

    if guess == number:
        print("Hooray! You guessed it right!")
    elif guess < number:
        print("It's bigger...")
    elif guess > number:
        print("It's not so big.")

Guess the number!
Is it... 2
It's bigger...
Is it... 5
It's bigger...
Is it... 10
It's not so big.
Is it... 7
Hooray! You guessed it right!

# Asks for a number.
# Prints if it is even or odd

number = float(input("Tell me a number: "))
if number % 2 == 0:
    print(int(number), "is even.")
elif number % 2 == 1:
    print(int(number), "is odd.")
else:
    print(number, "is very strange.")

Tell me a number: 3
3 is odd.

Tell me a number: 2
2 is even.

Tell me a number: 3.4895
3.4895 is very strange.

# keeps asking for numbers until 0 is entered.
# Prints the average value.

count = 0
sum = 0.0
number = 1 # set to something that will not exit the while loop immediately.

print("Enter 0 to exit the loop")

while number != 0:
    number = float(input("Enter a number: "))
    if number != 0:
        count = count + 1
        sum = sum + number
    if number == 0:
        print("The average was:", sum / count)

Enter 0 to exit the loop
Enter a number: 3
Enter a number: 5
Enter a number: 0
The average was: 4.0

Enter 0 to exit the loop
Enter a number: 1
Enter a number: 4
Enter a number: 3
Enter a number: 0
The average was: 2.66666666667

# keeps asking for numbers until count numbers have been entered.
# Prints the average value.

#Notice that we use an integer to keep track of how many numbers, 
# but floating point numbers for the input of each number
sum = 0.0

print("This program will take several numbers then average them")
count = int(input("How many numbers would you like to average: "))
current_count = 0

while current_count < count:
    current_count = current_count + 1
    print("Number", current_count)
    number = float(input("Enter a number: "))
    sum = sum + number

print("The average was:", sum / count)

This program will take several numbers then average them
How many numbers would you like to average: 2
Number 1
Enter a number: 3
Number 2
Enter a number: 5
The average was: 4.0

This program will take several numbers then average them
How many numbers would you like to average: 3
Number 1
Enter a number: 1
Number 2
Enter a number: 4
Number 3
Enter a number: 3
The average was: 2.66666666667

name = input('Your name: ')
if name == 'Bryn':
    print('That is a nice name.')
elif name == 'John Cleese':
    print('... some funny text.')
elif name == 'Michael Palin':
    print('... some funny text.')
else:
    print('You have a nice name.')

number = 7
guess = -1
count = 0

print("Guess the number!")
while guess != number:
    guess = int(input("Is it... "))
    count = count + 1
    if guess == number:
        print("Hooray! You guessed it right!")
    elif guess < number:
        print("It's bigger...")
    elif guess > number:
        print("It's not so big.")

if count > 3:
    print("That must have been complicated.")
else:
    print("Good job!")

number1 = float(input('1st number: '))
number2 = float(input('2nd number: '))
if number1 + number2 > 100:
    print('That is a big number.')

Height: 3
Width: 4
perimeter = 15

Height: 2
Width: 3
perimeter = 11

Height: 4
Width: 4
perimeter = 16

Height: 2
Width: 2
perimeter = 8

Height: 5
Width: 1
perimeter = 8

height = int(input("Height: "))
width = int(input("Width: "))
print("perimeter =", width + height + width + width)

. . . . 

number = 5
while number > 1:
    print(".",end=" ")
    number = number - 1
print()

a = 23
b = -23

if a < 0:
    a = -a
if b < 0:
    b = -b
if a == b:
    print("The absolute values of", a, "and", b, "are equal.")
else:
    print("The absolute values of", a, "and", b, "are different.")

The absolute values of 23 and 23 are equal.

a = 23
b = -23

def absolute_value(n):
    if n < 0:
        n = -n
    return n

if absolute_value(a) == absolute_value(b):
    print("The absolute values of", a, "and", b, "are equal.")
else:
    print("The absolute values of", a, "and", b, "are different.")

The absolute values of 23 and -23 are equal.

def hello():
    print("Hello")

def area(width, height):
    return width * height

def print_welcome(name):
    print("Welcome", name)

hello()
hello()

print_welcome("Fred")
w = 4
h = 5
print("width =", w, " height =", h, " area =", area(w, h))

Hello
Hello
Welcome Fred
width = 4  height = 5  area = 20

a = 4

def print_func():
    a = 17
    print("in print_func a =", a)

print_func()
print("a = ", a)

in print_func a = 17
a = 4

a_var = 10
b_var = 15
e_var = 25

def a_func(a_var):
    print("in a_func a_var =", a_var)
    b_var = 100 + a_var
    d_var = 2 * a_var
    print("in a_func b_var =", b_var)
    print("in a_func d_var =", d_var)
    print("in a_func e_var =", e_var)
    return b_var + 10

c_var = a_func(b_var)

print("a_var =", a_var)
print("b_var =", b_var)
print("c_var =", c_var)
print("d_var =", d_var)

in a_func a_var =  15
in a_func b_var =  115
in a_func d_var =  30
in a_func e_var =  25
a_var =  10
b_var =  15
c_var =  125
d_var = 

Traceback (most recent call last):
 File "C:\def2.py", line 19, in <module>
   print("d_var = ", d_var)
NameError: name 'd_var' is not defined

#! /usr/bin/python
#-*-coding: utf-8 -*-
# converts temperature to Fahrenheit or Celsius

def print_options():
    print("Options:")
    print(" 'p' print options")
    print(" 'c' convert from Celsius")
    print(" 'f' convert from Fahrenheit")
    print(" 'q' quit the program")

def celsius_to_fahrenheit(c_temp):
    return 9.0 / 5.0 * c_temp + 32

def fahrenheit_to_celsius(f_temp):
    return (f_temp - 32.0) * 5.0 / 9.0

choice = "p"
while choice != "q":
    if choice == "c":
        c_temp = float(input("Celsius temperature: "))
        print("Fahrenheit:", celsius_to_fahrenheit(c_temp))
        choice = input("option: ")
    elif choice == "f":
        f_temp = float(input("Fahrenheit temperature: "))
        print("Celsius:", fahrenheit_to_celsius(f_temp))
        choice = input("option: ")
    else:
        choice = "p"    #Alternatively choice != "q": so that print 
                        #when anything unexpected inputed
        print_options()
        choice = input("option: ")

Options:
 'p' print options
 'c' convert from celsius
 'f' convert from fahrenheit
 'q' quit the program
option: c
Celsius temperature: 30 
Fahrenheit: 86.0
option: f
Fahrenheit temperature: 60
Celsius: 15.5555555556
option: q

#! /usr/bin/python
#-*-coding: utf-8 -*-
# calculates a given rectangle area

def hello():
    print('Hello!')

def area(width, height):
    return width * height

def print_welcome(name):
    print('Welcome,', name)

def positive_input(prompt):
    number = float(input(prompt))
    while number <= 0:
        print('Must be a positive number')
        number = float(input(prompt))
    return number

name = input('Your Name: ')
hello()
print_welcome(name)
print()
print('To find the area of a rectangle,')
print('enter the width and height below.')
print()
w = positive_input('Width: ')
h = positive_input('Height: ')

print('Width =', w, ' Height =', h, ' so Area =', area(w, h))

Your Name: Josh
Hello!
Welcome, Josh

To find the area of a rectangle,
enter the width and height below.

Width: -4
Must be a positive number
Width: 4
Height: 3
Width = 4  Height = 3  so Area = 12

def square(L):
    return L * L

def rectangle(width , height):
    return width * height

def circle(radius):
    return 3.14159 * radius ** 2

def options():
    print()
    print("Options:")
    print("s = calculate the area of a square.")
    print("c = calculate the area of a circle.")
    print("r = calculate the area of a rectangle.")
    print("q = quit")
    print()

print("This program will calculate the area of a square, circle or rectangle.")
choice = "x"
options()
while choice != "q":
    choice = input("Please enter your choice: ")
    if choice == "s":
        L = float(input("Length of square side: "))
        print("The area of this square is", square(L))
        options()
    elif choice == "c":
        radius = float(input("Radius of the circle: "))
        print("The area of the circle is", circle(radius))
        options()
    elif choice == "r":
        width = float(input("Width of the rectangle: "))
        height = float(input("Height of the rectangle: "))
        print("The area of the rectangle is", rectangle(width, height))
        options()
    elif choice == "q":
        print(" ",end="")
    else:
        print("Unrecognized option.")
        options()

def mult(a, b):
    if b == 0:
        return 0
    rest = mult(a, b - 1)
    value = a + rest
    return value
result = mult(3, 2)
print("3 * 2 = ", result)

def mult(a, b):
    if b == 0:
        return 0
    rest = mult(a, b - 1)
    value = a + rest
    return value

mult(3, 2)
3 + mult(3, 1)
3 + 3 + mult(3, 0)
3 + 3 + 0
3 + 3
6

#defines a function that calculates the factorial

def factorial(n):
    if n == 0:
        return 1
    if n<0:
        return "Error, negative numbers do not have factorial values!!"
    return n * factorial(n - 1)

print("2! =", factorial(2))
print("3! =", factorial(3))
print("4! =", factorial(4))
print("5! =", factorial(5))
print("-3! =", factorial(-3))

2! = 2
3! = 6
4! = 24
5! = 120
-3! = Error, negative values do not have factorial values!!

def count_down(n):
    print(n)
    if n > 0:
        return count_down(n-1)

count_down(5)

5
4
3
2
1
0

which_one = int(input("What month (1-12)? "))
months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']

if 1 <= which_one <= 12:
    print("The month is", months[which_one - 1])

What month (1-12)? 3
The month is March

demolist = ["life", 42, "the universe", 6, "and", 9]
print("demolist = ",demolist)
demolist.append("everything")
print("after 'everything' was appended demolist is now:")
print(demolist)
print("len(demolist) =", len(demolist))
print("demolist.index(42) =", demolist.index(42))
print("demolist[1] =", demolist[1])

# Next we will loop through the list
for c in range(len(demolist)):
    print("demolist[", c, "] =", demolist[c])

del demolist[2]
print("After 'the universe' was removed demolist is now:")
print(demolist)
if "life" in demolist:
    print("'life' was found in demolist")
else:
    print("'life' was not found in demolist")

if "amoeba" in demolist:
    print("'amoeba' was found in demolist")

if "amoeba" not in demolist:
    print("'amoeba' was not found in demolist")

another_list = [42,7,0,123]
another_list.sort()
print("The sorted another_list is", another_list)

demolist =  ['life', 42, 'the universe', 6, 'and', 9]
after 'everything' was appended demolist is now:
['life', 42, 'the universe', 6, 'and', 9, 'everything']
len(demolist) = 7
demolist.index(42) = 1
demolist[1] = 42
demolist[ 0 ] = life
demolist[ 1 ] = 42
demolist[ 2 ] = the universe
demolist[ 3 ] = 6
demolist[ 4 ] = and
demolist[ 5 ] = 9
demolist[ 6 ] = everything
After 'the universe' was removed demolist is now:
['life', 42, 6, 'and', 9, 'everything']
'life' was found in demolist
'amoeba' was not found in demolist
The sorted another_list is [0, 7, 42, 123]

for c in range(len(demolist)):
    print('demolist[', c, '] =', demolist[c])

for c, x in enumerate(demolist):
    print("demolist[", c, "] =", x)

"value"
menu_item = 0
namelist = []
while menu_item != 9:
    print("--------------------")
    print("1. Print the list")
    print("2. Add a name to the list")
    print("3. Remove a name from the list")
    print("4. Change an item in the list")
    print("9. Quit")
    menu_item = int(input("Pick an item from the menu: "))
    if menu_item == 1:
        current = 0
        if len(namelist) > 0:
            while current < len(namelist):
                print(current, ".", namelist[current])
                current = current + 1
        else:
            print("List is empty")
    elif menu_item == 2:
        name = input("Type in a name to add: ")
        namelist.append(name)
    elif menu_item == 3:
        del_name = input("What name would you like to remove: ")
        if del_name in namelist:
            # namelist.remove(del_name) would work just as fine
            item_number = namelist.index(del_name)
            del namelist[item_number]
            # The code above only removes the first occurrence of
            # the name.  The code below from Gerald removes all.
            # while del_name in namelist:
            #       item_number = namelist.index(del_name)
            #       del namelist[item_number]
        else:
            print(del_name, "was not found")
    elif menu_item == 4:
        old_name = input("What name would you like to change: ")
        if old_name in namelist:
            item_number = namelist.index(old_name)
            new_name = input("What is the new name: ")
            namelist[item_number] = new_name
        else:
            print(old_name, "was not found")

print("Goodbye")

--------------------
1. Print the list
2. Add a name to the list
3. Remove a name from the list
4. Change an item in the list
9. Quit

Pick an item from the menu: 2
Type in a name to add: Jack

Pick an item from the menu: 2
Type in a name to add: Jill

Pick an item from the menu: 1
0 . Jack
1 . Jill

Pick an item from the menu: 3
What name would you like to remove: Jack

Pick an item from the menu: 4
What name would you like to change: Jill
What is the new name: Jill Peters

Pick an item from the menu: 1
0 . Jill Peters

Pick an item from the menu: 9
Goodbye

current = 0
if len(namelist) > 0:
    while current < len(namelist):
        print(current, ".", namelist[current])
        current = current + 1
else:
    print("List is empty")

item_number = namelist.index(del_name)
del namelist[item_number]

old_name = input("What name would you like to change: ")
if old_name in namelist:
    item_number = namelist.index(old_name)
    new_name = input("What is the new name: ")
    namelist[item_number] = new_name
else:
   print(old_name, "was not found")

## This program runs a test of knowledge

# First get the test questions
# Later this will be modified to use file io.
def get_questions():
    # notice how the data is stored as a list of lists
    return [["What color is the daytime sky on a clear day? ", "blue"],
            ["What is the answer to life, the universe and everything? ", "42"],
            ["What is a three letter word for mouse trap? ", "cat"]]

# This will test a single question
# it takes a single question in
# it returns True if the user typed the correct answer, otherwise False

def check_question(question_and_answer):
    # extract the question and the answer from the list
    # This function takes a list with two elements, a question and an answer.  
    question = question_and_answer[0]   
    answer = question_and_answer[1]
    # give the question to the user
    given_answer = input(question)
    # compare the user's answer to the tester's answer
    if answer == given_answer:
        print("Correct")
        return True
    else:
        print("Incorrect, correct was:", answer)
        return False

# This will run through all the questions
def run_test(questions):
    if len(questions) == 0:
        print("No questions were given.")
        # the return exits the function
        return
    index = 0
    right = 0
    while index < len(questions):
        # Check the question
        #Note that this is extracting a question and answer list from the list of lists.
        if check_question(questions[index]): 
            right = right + 1
        # go to the next question
        index = index + 1
    # notice the order of the computation, first multiply, then divide
    print("You got", right * 100 / len(questions),\
           "% right out of", len(questions))

# now let's get the questions from the get_questions function, and
# send the returned list of lists as an argument to the run_test function.

run_test(get_questions())

What color is the daytime sky on a clear day? green
Incorrect, correct was: blue
What is the answer to life, the universe and everything? 42
Correct
What is a three letter word for mouse trap? cat
Correct
You got 66 % right out of 3

## This program runs a test of knowledge

questions = [["What color is the daytime sky on a clear day? ", "blue"],
             ["What is the answer to life, the universe and everything? ", "42"],
             ["What is a three letter word for mouse trap? ", "cat"],
             ["What noise does a truly advanced machine make?", "ping"]]

# This will test a single question
# it takes a single question in
# it returns True if the user typed the correct answer, otherwise False

def check_question(question_and_answer):
    # extract the question and the answer from the list
    question = question_and_answer[0]
    answer = question_and_answer[1]
    # give the question to the user
    given_answer = input(question)
    # compare the user's answer to the testers answer
    if answer == given_answer:
        print("Correct")
        return True
    else:
        print("Incorrect, correct was:", answer)
        return False

# This will run through all the questions

def run_test(questions):

    if len(questions) == 0:
        print("No questions were given.")
        # the return exits the function
        return
    index = 0
    right = 0
    while index < len(questions):
        # Check the question
        if check_question(questions[index]):
            right = right + 1
        # go to the next question
        index = index + 1
    # notice the order of the computation, first multiply, then divide
    print("You got", right * 100 / len(questions),
           "% right out of", len(questions))

#showing a list of questions and answers
def showquestions():
    q = 0
    while q < len(questions):
        a = 0
        print("Q:" , questions[q][a])
        a = 1
        print("A:" , questions[q][a])
        q = q + 1

# now let's define the menu function
def menu():
    print("-----------------")
    print("Menu:")
    print("1 - Take the test")
    print("2 - View a list of questions and answers")
    print("3 - View the menu")
    print("5 - Quit")
    print("-----------------")

choice = "3"
while choice != "5":
    if choice == "1":
        run_test(questions)
    elif choice == "2":
        showquestions()
    elif choice == "3":
        menu()
    print()
    choice = input("Choose your option from the menu above: ")

one_to_ten = range(1, 11)
for count in one_to_ten:
    print(count)

1
2
3
4
5
6
7
8
9
10

for count in range(1, 11):
    print(count)

>>> range(1, 10)
range(1, 10)
>>> list(range(1, 10))
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(range(-32, -20))
[-32, -31, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21]
>>> list(range(5,21))
[5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
>>> list(range(5))
[0, 1, 2, 3, 4]
>>> list(range(21, 5))
[]

demolist = ['life', 42, 'the universe', 6, 'and', 7, 'everything']
for item in demolist:
    print("The current item is:",item)

The current item is: life
The current item is: 42
The current item is: the universe
The current item is: 6
The current item is: and
The current item is: 7
The current item is: everything

list = [2, 4, 6, 8]
sum = 0
for num in list:
    sum = sum + num

print("The sum is:", sum)

The sum is: 20

list = [4, 5, 7, 8, 9, 1, 0, 7, 10]
list.sort()
prev = None
for item in list:
    if prev == item:
        print("Duplicate of", prev, "found")
    prev = item

Duplicate of 7 found

l = [4, 5, 7, 8, 9, 1, 0, 7, 10]
print("l = [4, 5, 7, 8, 9, 1, 0, 7, 10]", "\t\tl:", l)
l.sort()
print("l.sort()", "\t\tl:", l)
prev = l[0]
print("prev = l[0]", "\t\tprev:", prev)
del l[0]
print("del l[0]", "\t\tl:", l)
for item in l:
    if prev == item:
        print("Duplicate of", prev, "found")
    print("if prev == item:", "\t\tprev:", prev, "\titem:", item)
    prev = item
    print("prev = item", "\t\tprev:", prev, "\titem:", item)

l = [4, 5, 7, 8, 9, 1, 0, 7, 10]        l: [4, 5, 7, 8, 9, 1, 0, 7, 10]
l.sort()                l: [0, 1, 4, 5, 7, 7, 8, 9, 10]
prev = l[0]             prev: 0
del l[0]                l: [1, 4, 5, 7, 7, 8, 9, 10]
if prev == item:        prev: 0         item: 1
prev = item             prev: 1         item: 1
if prev == item:        prev: 1         item: 4
prev = item             prev: 4         item: 4
if prev == item:        prev: 4         item: 5
prev = item             prev: 5         item: 5
if prev == item:        prev: 5         item: 7
prev = item             prev: 7         item: 7
Duplicate of 7 found
if prev == item:        prev: 7         item: 7
prev = item             prev: 7         item: 7
if prev == item:        prev: 7         item: 8
prev = item             prev: 8         item: 8
if prev == item:        prev: 8         item: 9
prev = item             prev: 9         item: 9
if prev == item:        prev: 9         item: 10
prev = item             prev: 10        item: 10

a = 1
b = 1
for c in range(1, 10):
    print(a, end=" ")
    n = a + b
    a = b
    b = n

1 1 2 3 5 8 13 21 34

a = 6
b = 7
c = 42
print(1, a == 6)
print(2, a == 7)
print(3, a == 6 and b == 7)
print(4, a == 7 and b == 7)
print(5, not a == 7 and b == 7)
print(6, a == 7 or b == 7)
print(7, a == 7 or b == 6)
print(8, not (a == 7 and b == 6))
print(9, not a == 7 and b == 6)

1 True
2 False
3 True
4 False
5 True
6 True
7 False
8 True
9 False

print(1, a == 6)
print(2, a == 7)

list = ["Life", "The Universe", "Everything", "Jack", "Jill", "Life", "Jill"]

# make a copy of the list. See the More on Lists chapter to explain what [:] means.
copy = list[:]
# sort the copy
copy.sort()
prev = copy[0]
del copy[0]

count = 0

# go through the list searching for a match
while count < len(copy) and copy[count] != prev:
    prev = copy[count]
    count = count + 1

# If a match was not found then count can't be < len
# since the while loop continues while count is < len
# and no match is found

if count < len(copy):
    print("First Match:", prev)

First Match: Jill

>>> 'a' == ('a' or 'b')
>>> 'b' == ('a' or 'b')
>>> 'a' == ('a' and 'b')
>>> 'b' == ('a' and 'b')

>>> 'a' == ('a' or 'b')
True
>>> 'b' == ('a' or 'b')
False
>>> 'a' == ('a' and 'b')
False 
>>> 'b' == ('a' and 'b')
True

>>> 'a' == ('a' or 'b')  # Look at parentheses first, so evaluate expression "('a' or 'b')"
                           # 'a' is a nonempty string, so the first value is True
                           # Return that first value: 'a'
>>> 'a' == 'a'           # the string 'a' is equivalent to the string 'a', so expression is True
True

>>> 'b' == ('a' or 'b')  # Look at parentheses first, so evaluate expression "('a' or 'b')"
                           # 'a' is a nonempty string, so the first value is True
                           # Return that first value: 'a'
>>> 'b' == 'a'           # the string 'b' is not equivalent to the string 'a', so expression is False
False 

>>> 'a' == ('a' and 'b') # Look at parentheses first, so evaluate expression "('a' and 'b')"
                           # 'a' is a nonempty string, so the first value is True, examine second value
                           # 'b' is a nonempty string, so second value is True
                           # Return that second value as result of whole expression: 'b'
>>> 'a' == 'b'           # the string 'a' is not equivalent to the string 'b', so expression is False
False

>>> 'b' == ('a' and 'b') # Look at parentheses first, so evaluate expression "('a' and 'b')"
                           # 'a' is a nonempty string, so the first value is True, examine second value
                           # 'b' is a nonempty string, so second value is True
                           # Return that second value as result of whole expression: 'b'
>>> 'b' == 'b'           # the string 'b' is equivalent to the string 'b', so expression is True
True 

>>> 'a' == 'a' or 'a' == 'b' 
True
>>> 'b' == 'a' or 'b' == 'b' 
True
>>> 'a' == 'a' and 'a' == 'b' 
False
>>> 'b' == 'a' and 'b' == 'b' 
False

## This program asks a user for a name and a password.
# It then checks them to make sure that the user is allowed in.

name = input("What is your name? ")
password = input("What is the password? ")
if name == "Josh" and password == "Friday":
    print("Welcome Josh")
elif name == "Fred" and password == "Rock":
    print("Welcome Fred")
else:
    print("I don't know you.")

What is your name? Josh
What is the password? Friday
Welcome Josh

What is your name? Bill
What is the password? Money
I don't know you.

print("Try to guess my name!")
count = 1
name = "guilherme"
guess = input("What is my name? ")
while count < 3 and guess.lower() != name:    # .lower allows things like Guilherme to still match
    print("You are wrong!")
    guess = input("What is my name? ")
    count = count + 1

if guess.lower() != name:
    print("You are wrong!") # this message isn't printed in the third chance, so we print it now
    print("You ran out of chances.")
else:
    print("Yes! My name is", name + "!")

def print_menu():
    print('1. Print Phone Numbers')
    print('2. Add a Phone Number')
    print('3. Remove a Phone Number')
    print('4. Lookup a Phone Number')
    print('5. Quit')
    print()

numbers = {}
menu_choice = 0
print_menu()
while menu_choice != 5:
    menu_choice = int(input("Type in a number (1-5): "))
    if menu_choice == 1:
        print("Telephone Numbers:")
        for x in numbers.keys():
            print("Name: ", x, "\tNumber:", numbers[x])
        print()
    elif menu_choice == 2:
        print("Add Name and Number")
        name = input("Name: ")
        phone = input("Number: ")
        numbers[name] = phone
    elif menu_choice == 3:
        print("Remove Name and Number")
        name = input("Name: ")
        if name in numbers:
            del numbers[name]
        else:
            print(name, "was not found")
    elif menu_choice == 4:
        print("Lookup Number")
        name = input("Name: ")
        if name in numbers:
            print("The number is", numbers[name])
        else:
            print(name, "was not found")
    elif menu_choice != 5:
        print_menu()

1. Print Phone Numbers
2. Add a Phone Number
3. Remove a Phone Number
4. Lookup a Phone Number
5. Quit

Type in a number (1-5): 2
Add Name and Number
Name: Joe
Number: 545-4464
Type in a number (1-5): 2
Add Name and Number
Name: Jill
Number: 979-4654
Type in a number (1-5): 2
Add Name and Number
Name: Fred
Number: 132-9874
Type in a number (1-5): 1
Telephone Numbers:
Name: Jill     Number: 979-4654
Name: Joe      Number: 545-4464
Name: Fred     Number: 132-9874

Type in a number (1-5): 4
Lookup Number
Name: Joe
The number is 545-4464
Type in a number (1-5): 3
Remove Name and Number
Name: Fred
Type in a number (1-5): 1
Telephone Numbers:
Name: Jill     Number: 979-4654
Name: Joe      Number: 545-4464

Type in a number (1-5): 5

for x in numbers.keys():
    print("Name:", x, "\tNumber:", numbers[x])

if name in numbers:
    del numbers[name]

if name in numbers:
    print("The number is", numbers[name])

max_points = [25, 25, 50, 25, 100]
assignments = ['hw ch 1', 'hw ch 2', 'quiz   ', 'hw ch 3', 'test']
students = {'#Max': max_points}

def print_menu():
    print("1. Add student")
    print("2. Remove student")
    print("3. Print grades")
    print("4. Record grade")
    print("5. Print Menu")
    print("6. Exit")

def print_all_grades():
    print('\t', end=' ')
    for i in range(len(assignments)):
        print(assignments[i], '\t', end=' ')
    print()
    keys = list(students.keys())
    keys.sort()
    for x in keys:
        print(x, '\t', end=' ')
        grades = students[x]
        print_grades(grades)

def print_grades(grades):
    for i in range(len(grades)):
        print(grades[i], '\t', end=' ')
    print()

print_menu()
menu_choice = 0
while menu_choice != 6:
    print()
    menu_choice = int(input("Menu Choice (1-6): "))
    if menu_choice == 1:
        name = input("Student to add: ")
        students[name] = [0] * len(max_points)
    elif menu_choice == 2:
        name = input("Student to remove: ")
        if name in students:
            del students[name]
        else:
            print("Student:", name, "not found")
    elif menu_choice == 3:
        print_all_grades()
    elif menu_choice == 4:
        print("Record Grade")
        name = input("Student: ")
        if name in students:
            grades = students[name]
            print("Type in the number of the grade to record")
            print("Type a 0 (zero) to exit")
            for i in range(len(assignments)):
                print(i + 1, assignments[i], '\t', end=' ')
            print()
            print_grades(grades)
            which = 1234
            while which != -1:
                which = int(input("Change which Grade: "))
                which -= 1    #same as which = which - 1
                if 0 <= which < len(grades):
                    grade = int(input("Grade: "))
                    grades[which] = grade
                elif which != -1:
                    print("Invalid Grade Number")
        else:
            print("Student not found")
    elif menu_choice != 6:
        print_menu()

1. Add student
2. Remove student
3. Print grades
4. Record grade
5. Print Menu
6. Exit

Menu Choice (1-6): 3
       hw ch 1         hw ch 2         quiz            hw ch 3         test 
#Max    25              25              50              25              100 

Menu Choice (1-6): 5
1. Add student
2. Remove student
3. Print grades
4. Record grade
5. Print Menu
6. Exit

Menu Choice (1-6): 1
Student to add: Bill

Menu Choice (1-6): 4
Record Grade
Student: Bill
Type in the number of the grade to record
Type a 0 (zero) to exit
1   hw ch 1     2   hw ch 2     3   quiz        4   hw ch 3     5   test 
0               0               0               0               0 
Change which Grade: 1
Grade: 25
Change which Grade: 2
Grade: 24
Change which Grade: 3
Grade: 45
Change which Grade: 4
Grade: 23
Change which Grade: 5
Grade: 95
Change which Grade: 0

Menu Choice (1-6): 3
       hw ch 1         hw ch 2         quiz            hw ch 3         test 
#Max    25              25              50              25              100
Bill    25              24              45              23              95 

Menu Choice (1-6): 6

def print_all_grades():
    print('\t',end=" ")
    for i in range(len(assignments)):
        print(assignments[i], '\t',end=" ")
    print()
    keys = list(students.keys())
    keys.sort()
    for x in keys:
        print(x, '\t',end=' ')
        grades = students[x]
        print_grades(grades)

import calendar
year = int(input("Type in the year number: "))
calendar.prcal(year)

Type in the year number: 2001

                                 2001                                  

       January                  February                    March      

Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su      Mo Tu We Th Fr Sa Su
1  2  3  4  5  6  7                1  2  3  4                1  2  3  4     
8  9 10 11 12 13 14       5  6  7  8  9 10 11       5  6  7  8  9 10 11
15 16 17 18 19 20 21      12 13 14 15 16 17 18      12 13 14 15 16 17 18     
22 23 24 25 26 27 28      19 20 21 22 23 24 25      19 20 21 22 23 24 25     
29 30 31                  26 27 28                  26 27 28 29 30 31        

from calendar import prcal

year = int(input("Type in the year number: "))
prcal(year)

from time import time, ctime

prev_time = ""
while True:
    the_time = ctime(time())
    if prev_time != the_time:
        print("The time is:", ctime(time()))
        prev_time = the_time

The time is: Sun Aug 20 13:40:04 2000
The time is: Sun Aug 20 13:40:05 2000
The time is: Sun Aug 20 13:40:06 2000
The time is: Sun Aug 20 13:40:07 2000

Traceback (innermost last):
 File "clock.py", line 5, in ?
    the_time = ctime(time())

KeyboardInterrupt

from random import randint
number = randint(0, 99)
guess = -1
while guess != number: 
    guess = int(input ("Guess a number: "))
    if guess > number:
        print("Too high")
    elif guess < number:
            print("Too low")
print("Just right")

import module

if __name__ == '__main__':
    pass

py3 -m pip install module

pip install module

>>> some_numbers = ['zero', 'one', 'two', 'three', 'four', 'five']
>>> some_numbers[0]
'zero'
>>> some_numbers[4]
'four'
>>> some_numbers[5]
'five'

>>> some_numbers[len(some_numbers) - 1]
'five'
>>> some_numbers[len(some_numbers) - 2]
'four'
>>> some_numbers[-1]
'five'
>>> some_numbers[-2]
'four'
>>> some_numbers[-6]
'zero'

>>> things = [0, 'Fred', 2, 'S.P.A.M.', 'Stocking', 42, "Jack", "Jill"]
>>> things[0]
0
>>> things[7]
'Jill'
>>> things[0:8]
[0, 'Fred', 2, 'S.P.A.M.', 'Stocking', 42, 'Jack', 'Jill']
>>> things[2:4]
[2, 'S.P.A.M.']
>>> things[4:7]
['Stocking', 42, 'Jack']
>>> things[1:5]
['Fred', 2, 'S.P.A.M.', 'Stocking']

>>> things[-4:-2]
['Stocking', 42]
>>> things[-4]
'Stocking'
>>> things[-4:6]
['Stocking', 42]

>>> things[:2]
[0, 'Fred']
>>> things[-2:]
['Jack', 'Jill']
>>> things[:3]
[0, 'Fred', 2]
>>> things[:-5]
[0, 'Fred', 2]

poem = ["<B>", "Jack", "and", "Jill", "</B>", "went", "up", "the",
        "hill", "to", "<B>", "fetch", "a", "pail", "of", "</B>",
        "water.", "Jack", "fell", "<B>", "down", "and", "broke",
        "</B>", "his", "crown", "and", "<B>", "Jill", "came",
        "</B>", "tumbling", "after"]

def get_bold(text):
    true = 1
    false = 0
    ## is_bold tells whether or not we are currently looking at 
    ## a bold section of text.
    is_bold = false
    ## start_block is the index of the start of either an unbolded 
    ## segment of text or a bolded segment.
    start_block = 0
    for index in range(len(text)):
        ## Handle a starting of bold text
        if text[index] == "<B>":
            if is_bold:
                print("Error: Extra Bold")
            ## print "Not Bold:", text[start_block:index]
            is_bold = true
            start_block = index + 1
        ## Handle end of bold text
        ## Remember that the last number in a slice is the index 
        ## after the last index used.
        if text[index] == "</B>":
            if not is_bold:
                print("Error: Extra Close Bold")
            print("Bold [", start_block, ":", index, "]", text[start_block:index])
            is_bold = false
            start_block = index + 1

get_bold(poem)

Bold [ 1 : 4 ] ['Jack', 'and', 'Jill']
Bold [ 11 : 15 ] ['fetch', 'a', 'pail', 'of']
Bold [ 20 : 23 ] ['down', 'and', 'broke']
Bold [ 28 : 30 ] ['Jill', 'came']

>>> a = [1, 2, 3]
>>> b = a
>>> print(b)
[1, 2, 3]
>>> b[1] = 10
>>> print(b)
[1, 10, 3]
>>> print(a)
[1, 10, 3]

>>> a = [1, 2, 3]
>>> b = a * 2
>>> print(a)
[1, 2, 3]
>>> print(b)
[1, 2, 3, 1, 2, 3]
>>> a[1] = 10
>>> print(a)
[1, 10, 3]
>>> print(b)
[1, 2, 3, 1, 2, 3]

>>> a = [1, 2, 3]
>>> b = a[:]
>>> b[1] = 10
>>> print(a)
[1, 2, 3]
>>> print(b)
[1, 10, 3]

>>> import copy
>>> a = [[1, 2, 3], [4, 5, 6]]
>>> b = a[:]
>>> c = copy.deepcopy(a)
>>> b[0][1] = 10
>>> c[1][1] = 12
>>> print(a)
[[1, 10, 3], [4, 5, 6]]
>>> print(b)
[[1, 10, 3], [4, 5, 6]]
>>> print(c)
[[1, 2, 3], [4, 12, 6]]

def shout(string):
    for character in string:
        print("Gimme an " + character)
        print("'" + character + "'")

shout("Lose")

def middle(string):
    print("The middle character is:", string[len(string) // 2])

middle("abcdefg")
middle("The Python Programming Language")
middle("Atlanta")

Gimme an L
'L'
Gimme an o
'o'
Gimme an s
's'
Gimme an e
'e'
The middle character is: d
The middle character is: r
The middle character is: a

def to_upper(string):
    ## Converts a string to upper case
    upper_case = ""
    for character in string:
        if 'a' <= character <= 'z':
            location = ord(character) - ord('a')
            new_ascii = location + ord('A')
            character = chr(new_ascii)
        upper_case = upper_case + character
    return upper_case

print(to_upper("This is Text"))

THIS IS TEXT

>>> # Integer to String
>>> 2
2
>>> repr(2)
'2'
>>> -123
-123
>>> repr(-123)
'-123'
>>> # String to Integer
>>> "23"
'23'
>>> int("23")
23
>>> "23" * 2
'2323'
>>> int("23") * 2
46
>>> # Float to String
>>> 1.23
1.23
>>> repr(1.23)
'1.23'
>>> # Float to Integer
>>> 1.23
1.23
>>> int(1.23)
1
>>> int(-1.23)
-1
>>> # String to Float
>>> float("1.23")
1.23
>>> "1.23" 
'1.23'
>>> float("123")
123.0

>>> repr(1)
'1'
>>> repr(234.14)
'234.14'
>>> repr([4, 42, 10])
'[4, 42, 10]'

>>> v = eval('123')
>>> print(v, type(v))
123 <type 'int'>
>>> v = eval('645.123')
>>> print(v, type(v))
645.123 <type 'float'>
>>> v = eval('[1, 2, 3]')
>>> print(v, type(v))
[1, 2, 3] <type 'list'>

>>> "This is a bunch of words".split()
['This', 'is', 'a', 'bunch', 'of', 'words']
>>> text = "First batch, second batch, third, fourth"
>>> text.split(",")
['First batch', ' second batch', ' third', ' fourth']

>>> list = text.split(",")
>>> len(list)
4
>>> list[-1]
' fourth'
>>> list = text.split(",", 2)
>>> len(list)
3
>>> list[-1]
' third, fourth'

[]
-0 == 0
text[1:4]
text
TRI
text[:5]
STRIN
first_index
last_index
text[:-1]
text[:5]
text[2]
R
text[:]
text[::-1]
text
STRING
GNIRTS
# This program requires an excellent understanding of decimal numbers.
def to_string(in_int):
    """Converts an integer to a string"""
    out_str = ""
    prefix = ""
    if in_int < 0:
        prefix = "-"
        in_int = -in_int
    while in_int // 10 != 0:
        out_str = str(in_int % 10) + out_str
        in_int = in_int // 10
    out_str = str(in_int % 10) + out_str
    return prefix + out_str

def to_int(in_str):
    """Converts a string to an integer"""
    out_num = 0
    if in_str[0] == "-":
        multiplier = -1
        in_str = in_str[1:]
    else:
        multiplier = 1
    for c in in_str:
        out_num = out_num * 10 + int(c)
    return out_num * multiplier

print(to_string(2))
print(to_string(23445))
print(to_string(-23445))
print(to_int("14234"))
print(to_int("12345"))
print(to_int("-3512"))

2
23445
-23445
14234
12345
-3512

# Write a file
with open("test.txt", "wt") as out_file:
    out_file.write("This Text is going to out file\nLook at it and see!")

# Read a file
with open("test.txt", "rt") as in_file:
    text = in_file.read()

print(text)

This Text is going to out file
Look at it and see!

def print_numbers(numbers):
    print("Telephone Numbers:")
    for k, v in numbers.items():
        print("Name:", k, "\tNumber:", v)
    print()

def add_number(numbers, name, number):
    numbers[name] = number

def lookup_number(numbers, name):
    if name in numbers:
        return "The number is " + numbers[name]
    else:
        return name + " was not found"

def remove_number(numbers, name):
    if name in numbers:
        del numbers[name]
    else:
        print(name," was not found")

def load_numbers(numbers, filename):
    in_file = open(filename, "rt")
    while True:
        in_line = in_file.readline()
        if not in_line:
            break
        in_line = in_line[:-1]
        name, number = in_line.split(",")
        numbers[name] = number
    in_file.close()

def save_numbers(numbers, filename):
    out_file = open(filename, "wt")
    for k, v in numbers.items():
        out_file.write(k + "," + v + "\n")
    out_file.close()

def print_menu():
    print('1. Print Phone Numbers')
    print('2. Add a Phone Number')
    print('3. Remove a Phone Number')
    print('4. Lookup a Phone Number')
    print('5. Load numbers')
    print('6. Save numbers')
    print('7. Quit')
    print()

phone_list = {}
menu_choice = 0
print_menu()
while True:
    menu_choice = int(input("Type in a number (1-7): "))
    if menu_choice == 1:
        print_numbers(phone_list)
    elif menu_choice == 2:
        print("Add Name and Number")
        name = input("Name: ")
        phone = input("Number: ")
        add_number(phone_list, name, phone)
    elif menu_choice == 3:
        print("Remove Name and Number")
        name = input("Name: ")
        remove_number(phone_list, name)
    elif menu_choice == 4:
        print("Lookup Number")
        name = input("Name: ")
        print(lookup_number(phone_list, name))
    elif menu_choice == 5:
        filename = input("Filename to load: ")
        load_numbers(phone_list, filename)
    elif menu_choice == 6:
        filename = input("Filename to save: ")
        save_numbers(phone_list, filename)
    elif menu_choice == 7:
        break
    else:
        print_menu()

print("Goodbye")

1. Print Phone Numbers
2. Add a Phone Number
3. Remove a Phone Number
4. Lookup a Phone Number
5. Load numbers
6. Save numbers
7. Quit

Type in a number (1-7): 2
Add Name and Number
Name: Jill
Number: 1234
Type in a number (1-7): 2
Add Name and Number
Name: Fred
Number: 4321
Type in a number (1-7): 1
Telephone Numbers:
Name: Jill     Number: 1234
Name: Fred     Number: 4321

Type in a number (1-7): 6
Filename to save: numbers.txt
Type in a number (1-7): 7
Goodbye

1. Print Phone Numbers
2. Add a Phone Number
3. Remove a Phone Number
4. Lookup a Phone Number
5. Load numbers
6. Save numbers
7. Quit

Type in a number (1-7): 5
Filename to load: numbers.txt
Type in a number (1-7): 1
Telephone Numbers:
Name: Jill     Number: 1234
Name: Fred     Number: 4321

Type in a number (1-7): 7
Goodbye

def load_numbers(numbers, filename):
    in_file = open(filename, "rt")
    while True:
        in_line = in_file.readline()
        if not in_line:
            break
        in_line = in_line[:-1]
        name, number = in_line.split(",")
        numbers[name] = number
    in_file.close()

def save_numbers(numbers, filename):
    out_file = open(filename, "wt")
    for k, v in numbers.items():
        out_file.write(k + "," + v + "\n")
    out_file.close()

import subprocess
def main():
    try:
        print("This small program invokes the print function in the Notepad application")
        #Lets print the file we created in the program above
        subprocess.call(['notepad','/p','numbers.txt'])
    except WindowsError:
        print("The called subprocess does not exist, or cannot be called.")

main()

assignments = ['hw ch 1', 'hw ch 2', 'quiz   ', 'hw ch 3', 'test']
students = { }

def load_grades(gradesfile):
    inputfile = open(gradesfile, "r")
    grades = [ ]
    while True:
        student_and_grade = inputfile.readline()
        student_and_grade = student_and_grade[:-1]
        if not student_and_grade:
            break
        else:
            studentname, studentgrades = student_and_grade.split(",")
            studentgrades = studentgrades.split(" ")
            students[studentname] = studentgrades
    inputfile.close()
    print("Grades loaded.")

def save_grades(gradesfile):
    outputfile = open(gradesfile, "w")
    for k, v in students.items():
        outputfile.write(k + ",")
        for x in v:
            outputfile.write(str(x) + " ")
        outputfile.write("\n")
    outputfile.close()
    print("Grades saved.")

def print_menu():
    print("1. Add student")
    print("2. Remove student")
    print("3. Load grades")
    print("4. Record grade")
    print("5. Print grades")
    print("6. Save grades")
    print("7. Print Menu")
    print("9. Quit")

def print_all_grades():
    if students:
        keys = sorted(students.keys())
        print('\t', end=' ')
        for x in assignments:
            print(x, '\t', end=' ')
        print()
        for x in keys:
            print(x, '\t', end=' ')
            grades = students[x]
            print_grades(grades)
    else:
        print("There are no grades to print.")

def print_grades(grades):
    for x in grades:
        print(x, '\t', end=' ')
    print()

print_menu()
menu_choice = 0
while menu_choice != 9:
    print()
    menu_choice = int(input("Menu Choice: "))
    if menu_choice == 1:
        name = input("Student to add: ")
        students[name] = [0] * len(assignments)
    elif menu_choice == 2:
        name = input("Student to remove: ")
        if name in students:
            del students[name]
        else:
            print("Student:", name, "not found")
    elif menu_choice == 3:
        gradesfile = input("Load grades from which file? ")
        load_grades(gradesfile)
    elif menu_choice == 4:
        print("Record Grade")
        name = input("Student: ")
        if name in students:
            grades = students[name]
            print("Type in the number of the grade to record")
            print("Type a 0 (zero) to exit")
            for i,x in enumerate(assignments):
                print(i + 1, x, '\t', end=' ')
            print()
            print_grades(grades)
            which = 1234
            while which != -1:
                which = int(input("Change which Grade: "))
                which -= 1
                if 0 <= which < len(grades):
                    grade = input("Grade: ") # Change from float(input()) to input() to avoid an error when saving
                    grades[which] = grade
                elif which != -1:
                    print("Invalid Grade Number")
        else:
            print("Student not found")
    elif menu_choice == 5:
        print_all_grades()
    elif menu_choice == 6:
        gradesfile = input("Save grades to which file? ")
        save_grades(gradesfile)
    elif menu_choice != 9:
        print_menu()

with open("in_test.txt", "rt") as in_file:
    with open("out_test.txt", "wt") as out_file:
        text = in_file.read()
        data = parse(text)
        results = encode(data)
        out_file.write(results)
    print( "All done." )

print("Type Control C or -1 to exit")
number = 1
while number != -1:
   number = int(input("Enter a number: "))
   print("You entered:", number)

Traceback (most recent call last):
 File "try_less.py", line 4, in <module>
   number = int(input("Enter a number: "))
ValueError: invalid literal for int() with base 10: '\\@#&'

print("Type Control C or -1 to exit")
number = 1
while number != -1:
    try:
        number = int(input("Enter a number: "))
        print("You entered:", number)
    except ValueError:
        print("That was not a number.")

def print_menu():
	print('1. Print Phone Numbers')
	print('2. Add a Phone Number')
	print('3. Remove a Phone Number')
	print('4. Lookup a Phone Number')
	print('5. Quit')
	print()

numbers = {}
menu_choice = 0
print_menu()
while menu_choice != 5:
	try:
		menu_choice = int(input("Type in a number (1-5): "))
		if menu_choice == 1:
			print("Telephone Numbers:")
			for x in numbers.keys():
				print("Name: ", x, "\tNumber:", numbers[x])
			print()
		elif menu_choice == 2:
			print("Add Name and Number")
			name = input("Name: ")
			phone = input("Number: ")
			numbers[name] = phone
		elif menu_choice == 3:
			print("Remove Name and Number")
			name = input("Name: ")
			if name in numbers:
				del numbers[name]
			else:
				print(name, "was not found")
		elif menu_choice == 4:
			print("Lookup Number")
			name = input("Name: ")
			if name in numbers:
				print("The number is", numbers[name])
			else:
				print(name, "was not found")
		elif menu_choice != 5:
			print_menu()
	except ValueError:
		print("That was not a number.")

Non-Programmer's Tutorial for Python 3
← Authors	Print version	Intro →

Non-Programmer's Tutorial for Python 3
← Front matter	Print version	Hello, World →

Operation	Symbol	Example
Power (exponentiation)	`**`	`5 ** 2 == 25`
Multiplication	`*`	`2 * 3 == 6`
Division	`/`	`14 / 3 == 4.666666666666667`
Integer Division	`//`	`14 // 3 == 4`
Remainder (modulo)	`%`	`14 % 3 == 2`
Addition	`+`	`1 + 2 == 3`
Subtraction	`-`	`4 - 3 == 1`

Non-Programmer's Tutorial for Python 3
← Intro	Print version	Who Goes There? →

Operation	Symbol	Example
Repetition	`*`	`"i" * 5 == "iiiii"`
Concatenation	`+`	`"Hello, " + "World!" == "Hello, World!"`

example	explanation
`demolist[2]`	accesses the element at index 2
`demolist[2] = 3`	sets the element at index 2 to be 3
`del demolist[2]`	removes the element at index 2
`len(demolist)`	returns the length of `demolist`
`"value" in demolist`	is True if `"value"` is an element in `demolist`
`"value" not in demolist`	is True if `"value"` is not an element in `demolist`
`another_list.sort()`	sorts `another_list`. Note that the list must be all numbers or all strings to be sorted.
`demolist.index("value")`	returns the index of the first place that `"value"` occurs
`demolist.append("value")`	adds an element `"value"` at the end of the list
`demolist.remove("value")`	removes the first occurrence of value from `demolist` (same as `del demolist[demolist.index("value")]`)

True	False
True	False
1	0
Numbers other than zero	The string 'None'
Nonempty strings	Empty strings
Nonempty lists	Empty lists
Nonempty dictionaries	Empty dictionaries

		0		1		2		...		-2		-1
		↓		↓		↓		↓		↓		↓		↓
text =	"		S		T		R		I		N		G		"
		↑												↑
		[:												:]

Front matter

Other resources

Intro

First things first

Installing Python

Linux, BSD, and Unix users

Mac users

Windows users

Configuring your PATH environment variable

Interactive Mode

Creating and Running Programs

Program file names

Using Python from the command line

Running Python Programs in *nix

Where to get help

Python documentation

Python user community

Using python online

Hello, World

What you should know

Printing

Terminology

\n in Printing

Expressions

Arithmetic expressions

Commenting in Python

Examples

Exercises

Footnotes

Who Goes There?

Input and Variables

Assignment

Examples

Exercises

Count to 10

While loops

Infinite loops or Never Ending Loop

Examples

Fibonacci sequence

Enter password

Exercises

Decisions

If statement

Examples

Exercises

Debugging

What is debugging?

What should the program do?

What does the program do?

How do I fix my program?

Defining Functions

Creating Functions

Variables in functions

Examples

Exercises

Advanced Functions Example

Recursion

Examples

Lists

Variables with more than one value

More features of lists

Examples

Exercises

For Loops

Boolean Expressions

A note on Boolean Operators

Examples

Exercises

Dictionaries

Using Modules

Exercises

Other modules

Creating your own module

The __name__ == __main__ trick

The pip module

More on Lists

Revenge of the Strings

Slicing strings (and lists)

Examples

File IO

The name == main trick