- CB 3.12,3.13 Developing Procedures

What is a procedure?

A procedure is a named group of code that has paramaters and return values. Procedures are known as methods or functions depending on the language.

A procedure executes the statements within it on the parameters to provide a return value.

What are parameters?

Paramaters are input values of a procedure that are specified by arguments.Arguments specify the values of the parameters when a procedure is called.

By creating theses algorithms the readibility of code increases and the complexity decreases. This is becasue a function’s name can tell the reader what action it will perform, and by calling it, the code becomes more clean and easy to understand.

What is a return value?

A return value is the value that is returned when a function or a method is called.

That return value can be assigned or printed

Procedures are used to create algorthims that can perform certain actions or return values. When a procedure returns a value, theis information must be stored in a variable for later use. However some procedures like the MOVE_FORWARD() perform an action, and don’t return a value. The image above provides an example of where procedures that don’t output a value would be used.

A 60$ item recieves a 20% discount and taxed at 8%.
PROCEDURE applyDiscount(cost, percentDiscounted)
{
    temp ← 100 - percentDiscounted
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}

price ← applyDiscount(60, 20)
This is how we get the final price with the discount by calling the procedure and assigning it to the price variable.


PROCEDURE applyTax(cost, percentTaxed)
{
    temp ← 100 + percentTaxed
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}
price ← applyTax(price, 8)
This applys the 8% tax to the price determined after the discount.

Popcorn Hack 1

Given the applyTax procedure above: How would you call the procedure to get it to find the price using cost = 50, and percentTaxed = 10, and what value will it return?

#code here
cost = 50
percentTaxed = 10
applyTax = (cost/percentTaxed) + cost
print(applyTax)

55.0

What Are Functions?

• Collections of code
• Divides large program into smaller chunks
• Better readability
• Less repetitive code
• More efficient code
• Good organization

What Are The Components of a Function?

• The function declaration
• The parameters (input). This is also referred to as an argument when a value is being passed to the actual function.
• The functionality
• The return value (output)
• Calling the function

# Defining Functions
#
# def function_name(parameter1, parameter2, etc..):
#     code here...
#
#     return return_value;

# return the value of parameter1 plus parameter2;
def add(parameter1, parameter2): # creates a function that takes in two parameters
    solution = parameter1 + parameter2; # sets solution to the sum of parameter1 and parameter2
    return solution; # return solution
    
print(add(5, 5)); # prints the return value of add(5,5)

10

Popcorn Hack 2:

1. Make a function that returns the difference of two numbers

# Code here
def sub(parameter1, parameter2): # creates a function that takes in two parameters
    solution = parameter1 - (parameter2); # sets solution to the sum of parameter1 and parameter2
    return solution; # return solution
    
print(sub(-10, -5))

-5

What is a Class?

• A class is an outline for a set of nested functions and variables.
• There are instance variables
• Functions
• Constructor method (Required)
• To String method
• Getter method
• Setter method

How Does a Class Work?

# Defining Classes
class person:
    def __init__(self, name, age, ): # constructor
        self.name = name;
        self.age = age;
    
    def getName(self): # method to create get name
        return self.name
     
    def getAge(self): # method to create get age
        return self.age
    
    def setName(self, name): # method to create set name
        self.name = name
        
    def setAge(self, age): # method to create set age
        self.age = age
        
    def yearOlder(self): # method to increment age by 1
        self.age += 1
        
    def __str__(self): # method that returns a string when the object is printed
        return (f"My name is {self.name} and I am {self.age} years old.")

Person1 = person("John Doe", 15);
print(Person1)


print(Person1);

My name is John Doe and I am 15 years old.
My name is John Doe and I am 15 years old.

Popcorn Hack 3:

1. Create a Car class which has the attributes model, vehicle name, and price

2. Create instances of the following cars

• Name: Honda Civic , Model Year: 2018 , Price: $13,000
• Name: Toyota Prius, Model Year: 2023 , Price: $28,000
• Name: Chevrolet Impala, Model Year: 2020 , Price: $22,000

class car(model, name, price):
    def model():
        hondaC = 2018
        toyatoP = 2023
        ChevyImpala = 2020
    def name():
        hondaC = "Honda Civic"
        toyatoP = "Toyatoa Prius"
        ChevyImpala = "Chevrolet Impala"
    def price():
        hondaC = "$13,000"
        toyatoP = "$28,000"
        ChevyImpala = "$22,000"

  File "/tmp/ipykernel_4266/4068592482.py", line 3
    def name():
    ^
IndentationError: expected an indented block after function definition on line 2

Homework:

Assignment 1: How do you use functions?

Create a turtle python function that...

1. Takes a single parameter as the number of sides
2. Outputs a shape corresponding to the number of sides
3. Call the function with the argument being a variable with the user input

Hint:

import turtle

pen = turtle.Turtle()

def shape(sides):
    angle = 360 / sides
    for _ in range(sides):
        pen.forward(50)
        pen.right(angle)

numsides = input('How many sides do you want in your shape? ')
shape(int(numsides))

# This line is needed to keep the window open after drawing
turtle.done()

# Real Assignment 1
def get_distinct_values(input_array):
    distinct_array = []  # Create an empty array to store distinct values
    
    for element in input_array:  # Iterate through the input array
        if element not in distinct_array:  # Check if the element is not already in distinct_array
            distinct_array.append(element)  # If not, add it to the distinct_array
    
    return distinct_array  # Return the array containing distinct values

# Test the function
arr1 = [2,1,3,2,0,2,0,0,4,2,0,0,0,2,0,0,1,2,3,0,7,4,5,2,1,2,3,4,6]
distinct_values = get_distinct_values(arr1)
print(distinct_values)

Assignment 2:

Create a student class that...

1. Has a constructor that takes three parameters as attributes
2. • email
   • name
   • grade
3. Three getter methods to access the name, email, and grade
4. Three setter methods to modify the name, email, and grade
5. A to string method that returns the three instance variables in this format - "My name is {name}. My email is {email}. My grade is {grade}
6. Create an instance of the class that corresponds with you

class Student:
    def __init__(self, email, name, grade):
        self.email = email
        self.name = name
        self.grade = grade

    def get_name(self):
        return self.name

    def get_email(self):
        return self.email

    def get_grade(self):
        return self.grade

    def set_name(self, name):
        self.name = name

    def set_email(self, email):
        self.email = email

    def set_grade(self, grade):
        self.grade = grade

    def to_string(self):
        return f"My name is {self.name}. My email is {self.email}. My grade is {self.grade}"

# Create an instance of the Student class
your_student = Student("your_email@example.com", "Your Name", 90)

# Test the to_string method
print(your_student.to_string())

My name is Your Name. My email is your_email@example.com. My grade is 90