- 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
DISPLAY applyTax(cost, 10)

#It will display 55 (dollars)

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)

Popcorn Hack 2:

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

# Code here
def difference(num1, num2):
    return abs(num1 - num2)

difference(-5, 3)

8

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);

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:
    def __init__(self, attribues, vehicle_name, price):
        self.attributes = attribues
        self.vehicle_name = vehicle_name
        self.price = price

mine = Car('Honda Civic', '2018', '13,000')
yours = Car('Toyota Prius', '2023', '28,000')
ours = Car('Chevrolet Impala', '2020', '22,000')

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

Template:

import turtle

# pen is the instance of Turtle which has methods that do certain actions

# Necessary methods:
# .forward(50) - moves the pen forward 50 units
# .right(angle) - turns the pen angle degrees right
# OR
# .left(angle) - turns the pen angle degrees left


def shape(sides):
  angle = (180 / sides) * (sides - 2) # Gets the interior angle of the shape
  for i in range(sides):
    turtle.forward(50) #go forward 50 pixels or whatever size it is 
    turtle.right(angle) #Create an interior angle from the angle calculated before

numsides = input('How many sides do yoUUUU wnat in YOUUUURRRR shape?!?!!?!: ')
shape(int(numsides))

Assignment #1 (Fixed)

def get_distinct_values(arr):
    distinct_values = []
    for item in arr:
        if item not in distinct_values:
            distinct_values.append(item)
    return distinct_values

# Test the function with the provided array
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_arr = get_distinct_values(arr1)
print(distinct_arr)

[2, 1, 3, 0, 4, 7, 5, 6]

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_email(self):
        return self.email

    def get_name(self):
        return self.name

    def get_grade(self):
        return self.grade

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

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

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

    def to_string(self):
        return f"My name is {self.name}, my email is {self.email}, and I am in {self.grade} grade."

your_student = Student("akhils25090@stu.powayusd.com", "Akhil Singamneni", "10th")
print(your_student.to_string())

My name is Akhil Singamneni, my email is akhils25090@stu.powayusd.com, and I am in 10th grade.