- 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
def applyTax(cost, tax):
    taxed = cost * tax/100
    finalCost = cost + taxed
    return finalCost
applyTax(50,10)

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)

Popcorn Hack 2:

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

# Code here
num1 = int(input("Enter a number"))
num2 = int(input("Enter a number to subtract from the original"))

def subtract(x, y):
    return x - y

subtract(num1, num2)

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:
    def __init__(self, model, name, price,):
        self.model = model
        self.name = name
        self.price = price
    
car1 = car("Honda Civic", 2018, 13000)
car2 = car("Toyota Prius", 2023, 28000)
car3 = car("Chevrolet Impala", 2020, 22000)

Homework:

Assignment 0: How do you use functions?

Create a turtle python function that...

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

Hint:

# Turtle does not work on school wifi. Copy paste into a replit if you wanna see if I did it right

import turtle

pen = turtle.Turtle()
angle = 0
sides = int(input("How many sides? "))
if sides == 1 or sides == 2:
    print("Please enter a SHAPE")
else:
    angle = 360/sides
    

for i in range(sides):
    pen.forward(30)
    pen.right(angle)
    i += 1

turtle.done()

Assignment 1

Create a function that...

Takes an array as the parameter
Returns the array of distinct values
Don't use test arrays

arr1 = []
arr2 = []

while True:
    add = input("Add a number. Enter 's' to stop")
    if add == "s":
        break
    arr1.append(int(add))
    if int(add) not in arr2:
        arr2.append(int(add))

print("Numbers inputed: ",arr1)
print("After duplicates removed: ",arr2)

Numbers inputed:  [2, 23, 34, 2, 2, 6, 45, 2, 34, 45, 21, 2, 2, 9]
After duplicates removed:  [2, 23, 34, 6, 45, 21, 9]

Assignment 2:

Create a student class that...

Has a constructor that takes three parameters as attributes
- email
- name
- grade
Three getter methods to access the name, email, and grade
Three setter methods to modify the name, email, and grade
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}
Create an instance of the class that corresponds with you

class person:
    def __init__(self, email, name, grade, ): # constructor
        self.email = email
        self.name = name
        self.grade = grade
    
    def getEmail(self): # method to create get email
        return self.email
    
    def getName(self): # method to create get name
        return self.name
    
    def getGrade(self): # method to create get grade
        return self.grade
    
    def setEmail(self, email): # method to create set email
        self.email = email
    
    def setName(self, name): # method to create set name
        self.name = name
        
    def setGrade(self, grade): # method to create set grade
        self.grade = grade
        
    def __str__(self): # method that returns a string when the object is printed
        return (f"My name is {self.name} and I am in {self.grade}th grade. My email is {self.email}")

trevor_huang = person('fake@gmail.com', 'Trevor Huang', 10)
print(trevor_huang)

My name is Trevor Huang and I am in 10th grade. My email is fake@gmail.com