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Functions [Live Lecture]

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Today’s Agenda

Announcements
Review: Anatomy of a function
Writing some functions
Find the error

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Today’s Agenda

Announcements
Review: Anatomy of a function
Writing some functions
Find the error

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Announcements

First quiz is next Thursday:

We will be using the Lockdown Browser
The exam will be during class on Thursday.

To help you study, practice doing the mini-quizzes. I will also post a practice quiz, which you should take using the Lockdown Browser, sometime before next Thursday (instructions to come).

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Today’s Agenda

Announcements
Review: Anatomy of a function
Writing some functions
Find the error

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Functions: header and body

def name_of_function(parameters):

statement 1

statement 2

...

return some_value

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HEADER�Specifies the name of the function and the data that it needs. Also called the SIGNATURE

BODY�One or more indented statements that the function will execute when called

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def name_of_function(parameters):

statement(s)

return some_value

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Keyword def marks the start of function header

A function name to uniquely identify it (snake case)

parameters (the way we pass data to a function)

colon (:) marks end of function header

function body has 1 or more statements, which have same indentation level (usually 4 spaces)

An optional return statement to return a value from the function

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Today’s Agenda

Announcements
Review: Anatomy of a function
Writing some functions
Find the error

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Activity 1: Area of a Square

Write a function called get_area_sq that calculates the area of a square. Your function will take 1 argument, the length of one of the sides (float), and return the area of the square.

Reminder: to do this, you’ll have to first create a brand new Python file in Idle first, then save it (e.g. practice.py)...and then create your function.

When you’re done, invoke your function as follows:

area_1 = get_area_sq(5.5)�area_2 = get_area_sq(8)�print(area_1, area_2)

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Activity 2: Area of a Rectangle

Now, write a function that returns the area of a rectangle. Give it a name that’s mnemonic. Consider:

How would the function signature (header) need to change? In other words, what data does it need to perform this calculation?
In light of the above, how would the calculation change?

When you’re done, invoke (call) your function with some different data to prove that it works.

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Activity 3: Surface Area of a Cube

Now, write a function that returns the surface area of a cube, based on the length of a single side of the cube. Give it a name that’s mnemonic. Consider:

What would the function signature (header) look like?
What gets returned?

If you can (optional), try and see if you can make use of the get_area_sq function that you just made.

When you’re done, invoke (call) your function with some different data to prove that it works.

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Activity 4: Surface area of a rectangular box

Finally, write a function to calculate the surface area of any box, given that you know its length, width, and height.

If you can (optional), try and see if you can make use of the get_area_rect (or whatever you called it) function that you just made.

Questions to ask yourself:

What data does this function need to work?
What does it need to return (if anything)

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Practice: Activity 8 & 9

# Consider the following code:

print('*' * 12)

print('Hello Varun!')

print('*' * 12)

print('\n')

# Write a function that prints a message for any name

# with enough stars to exactly match the length of the message.

# Hint: Use the len() function.

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Today’s Agenda

Announcements
Review: Anatomy of a function
Writing some functions
Find the error

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Find the Mistake

def area_of_square(length:int):

return length * length

def surface_area_of_cube(area:int):

area * 6

print(

'Surface area of a cube where side=10 feet is:',

surface_area_of_cube(area_of_square(10)),

'feet'

)

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