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CS 110

Input, multiplication, and math

Benjamin Dicken

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Announcements

Going to try breakout rooms
Public vs private posts on piazza
Reminder: Prep problems

The pattern

Read → Prep Problem → Video / (optional) live→ Repeat

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The Goal: House printing

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

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Comments

Lines starting in # are comments to the user
You can leave comments for yourself, of future readers of your code!

# This is come code that will print out two lines of text

print('He said, "What is up?"')

print("Joe's friend didn't reply.")

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Comments

It is typical to put a comment at the top of all code files
This is called a header comment or file comment
You should do this for all of your programs, including the Movies PA

#

# Author: Benjamin Dicken

# Class: CSc 110

# Description: A program that . . .

#

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Integers and Variables

We can also assign a name to a numeric value, instead of a string of characters
For the time being, we will be using integers

Integer: a number with no fractional or decimal representation

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Integers and Variables

We can also assign a name to a numeric value, instead of a string of characters
For the time being, we will be using integers

Integer: a number with no fractional or decimal representation

For example:

age = 32

years_in_service = 17

wing_width = 25

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What will this print out?

name = 'Joe'

age = 35

inches = 72

print('Hello', name)

print('you are', age, 'years old')

print('and', inches, 'inches tall')

Activity

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Multiplying a string

You can use the asterisk ( * ) to repeat a string any number of times

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Multiplying a string

You can use the asterisk ( * ) to repeat a string any number of times
For example

name = 'CSc' * 3

print(name)

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Multiplying a string

You can use the asterisk ( * ) to repeat a string any number of times
For example

name = 'CSc' * 3

print(name)

CScCScCSc

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Multiplying a string

You can use the asterisk ( * ) to repeat a string any number of times
For example

name = 'CSc' * 10

print(name)

CScCScCScCScCScCScCScCScCScCSc

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String Multiplication question

What will this print out? Don’t use your computer, use the whiteboard!

print('#' * 2)

print('#' * 4)

print('#' * 6)

print('#' * 8)

Activity

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String Multiplication question

What will this print out. Use your white board - no computers!

print(' ' * 5, 'A' * 1)

print(' ' * 4, 'B' * 3)

print(' ' * 3, 'C' * 5)

print(' ' * 2, 'D' * 7)

print(' ' * 1, 'E' * 9)

print(' ' * 0, 'F' * 11)

Activity

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Revisiting House printing

Write a program that allows us to print out a house of various widths
The user can tell the program how wide of a house to print

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

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Revisiting House printing

Write a program that allows us to print out a house of various widths
The user can tell the program how wide of a house to print

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

Let’s write it!

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Step 1

Write a program that just prints out one house size:

Here's a size 3 house:

___^___

/ \

| H |

|___H___|

Activity

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Step 1

1 print("Here's a size 3 house:")

2 print(" ___^___")

3 print("/ \ ")

4 print("| H |")

5 print("|___H___|")

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Step 2

Next, change the program to grab an input value

(Can still print just the size 3 house)

What size house should be printed? X

___^___

/ \

| H |

|___H___|

1 print("Here's a size 3 house:")

2 print(" ___^___")

3 print("/ \ ")

4 print("| H |")

5 print("|___H___|")

Activity

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Step 2

1 size = input('What size house should be printed? ')

2 print(" ___^___")

3 print("/ \ ")

4 print("| H |")

5 print("|___H___|")

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Step 3

Now, use this number to grow the width of the house

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

Activity

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Step 3

Now, use this number to grow the width of the house

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

Did you convert the input value to an integer?

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Converting an input value to a string

Does not work:

width = input('enter width: ')

print('-' * width)

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Converting an input value to a string

Does not work:

width = input('enter width: ')

print('-' * width)

Does work:

width = int(input('enter width: '))

print('-' * width)

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What about the space?

How can you get the house to match the solution with commas?

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What about the space?

How can you get the house to match the solution with commas?
Use string concatenation instead ( + )

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What about the space?

How can you get the house to match the solution with commas?
Use string concatenation instead ( + )

print('_' * 5, '^', '_' * 5)

_____ ^ _____

print('_' * 5 + '^' + '_' * 5)

_____^_____

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Step 3

Now, use this number to grow the width of the house

What size house should be printed? 3

___^___

/ \

| H |

|___H___|

What size house should be printed? 12

____________^____________

/ \

| H |

|____________H____________|

What size house should be printed? 7

_______^_______

/ \

| H |

|_______H_______|

What size house should be printed? 0

^

/ \

|H|

Activity

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house.py

size = int(input('What size house should be printed? '))

print(' ' + '_' * size + '^' + '_' * size + ' ')

print('/' + ' ' * size + ' ' + ' ' * size + '\\')

print('|' + ' ' * size + 'H' + ' ' * size + '|')

print('|' + '_' * size + 'H' + '_' * size + '|')

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Newlines

We’ve seen several escape sequences so far
An escape sequence is a sequence of characters that produces a particular character within a string

\' \" \\ What do these produce?

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Newlines

We’ve seen several escape sequences so far
An escape sequence is a sequence of characters that produces a particular character within a string

\' \" \\ What do these produce?
And now: \n

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What does it print?

a = int(input('input a: ')) # 5

b = int(input('input b: ')) # 2

o = '#' * a + '\n'

t = '|' * a + '\n'

print(o * b + t * b)

Activity

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What does this print?

a = int(input('input a: ')) # 10

b = int(input('input b: ')) # 1

o = '#' * a + '\n'

r = o * 2 + '\n\n'

print(o + r + o)

Activity

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Vertical Difference

In the house example, we had a program that could make houses of varying widths
What about a program that can produce output of varying heights?

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Smiles

In this case, your program should take a number as input
Make the face taller or shorter, based on the input value

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The Goal: Face printing

What size face should be printed? 0

///|\\\

/ 0 0 \

| I |

| \___/ |

\_____/

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The Goal: Face printing

What size face should be printed? 1

///|\\\

/ 0 0 \

| |

| I |

| |

| \___/ |

\_____/

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The Goal: Face printing

What size face should be printed? 3

///|\\\

/ 0 0 \

| |

| I |

| |

| \___/ |

\_____/

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Implement the face program!

The space between the eyes and nose and nose and mouth changes with varying sized faces
You can use other characters for the eyes, nose, hair

Activity

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Face Printing Step 1

Just get a face printing out
Don’t yet worry about adjusting the height

A face:

///|\\\

/ 0 0 \

| I |

| \___/ |

\_____/

Activity

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Face Printing Step 2

Accept the input value and convert it to an int

What size face should be printed? 3

///|\\\

/ 0 0 \

| I |

| \___/ |

\_____/

Activity

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Face Printing Step 3

Make the size adjustable!

What size face should be printed? 3

///|\\\

/ 0 0 \

| |

| I |

| |

| \___/ |

\_____/

What size face should be printed? 1

///|\\\

/ 0 0 \

| |

| I |

| |

| \___/ |

\_____/

What size face should be printed? 0

///|\\\

/ 0 0 \

| I |

| \___/ |

\_____/

Activity

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height = int(input('input: '))

print(' ///|\\\\\\')

print('/ 0 0 \\')

print('| |\n' * height, end="")

print('| I |')

print('| |\n' * height, end="")

print('| \___/ |')

print(' \_____/')

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Division in Python

What does it print out?

age = 35

half_age = age / 2

print('You' * half_age)

Activity

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Two numeric types: float and integer

An integer is a type of value that can represent numbers without decimals or fractions
A float can represent numbers with decimals

age = 35 # integer

score = 81.23 # float

height_meters = 1.8288 # float (6 feet)

print(type(age))

print(type(score))

print(type(height_meters))

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Division in Python

You can complete a division operation with the forward-slash ( / )
For example

age = 35

half_age = age / 2

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Division in Python

What does it print out?

a = 52 / 7

e = 27 / 5

c = int(a)

print(e, '#' * c, c)

print('#' * c, e)

print(e, a, e)

Activity

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5.4 ####### 7

####### 5.4

5.4 7.428571428571429 5.4

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Flag

Write a program that takes one value as input
This value will be used to determine the width of a flag

Enter flag size: 10

#####-----

----------

Enter flag size: 20

##########----------

--------------------

Enter flag size: 30

###############---------------

------------------------------

Activity

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flag

width = int(input('Enter flag size: '))

half_width = int(width / 2)

print()

print('#' * half_width + '-' * half_width)

print('-' * width)

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Flag (version B)

Write a program that takes TWO values as input
This value will be used to determine the width and height of a flag

Enter flag width: 10

Enter flag height: 4

#####-----

----------

Enter flag width: 20

Enter flag height: 6

##########----------

--------------------

Enter flag width: 30

Enter flag height: 8

###############---------------

------------------------------

Activity

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Flag (version B)

width = int(input('Enter flag width: '))

height = int(input('Enter flag height: '))

half_width = int(width / 2)

half_height = int(height / 2)

print()

upper_row = '#' * half_width + '-' * half_width + '\n'

lower_row = '-' * width + '\n'

print(upper_row * half_height, end='')

print(lower_row * half_height)